Soil Contamination in Home Gardens
While growing your own food can be incredibly rewarding, it’s important to be mindful of the soil quality in your garden. Soil contamination is an issue in some gardens, and it can pose significant risks to both the environment and human health. Contamination can occur in any garden but gardens set in older houses or in urban areas with an industrial past are more likely to be affected. The good news is that soil contamination needn't mean the end to your gardening journey; there are easy steps that you can take to garden and grow food safely.
How Does Soil Become Contaminated?
Urban soils can be contaminated with a variety of heavy metals transported by air, soil or water. In urban areas past industrial activities, urbanisation, the use of lead paint and transportation infrastructure have all left their mark on garden soil. Common contaminants include lead, arsenic, cadmium, chromium and zinc.
Lead contamination in particular is a significant concern, especially in areas with older buildings where lead-based paints may have been used. Lead can also be present in soil near roads where pollutants from seven decades of leaded petrol use may have become persistent in the environment. According to the EPA’s GardenSafe initiative, soil in urban areas can also be contaminated by other pollutants from industrial activity, construction, or even past use of pesticides and fertilisers.
Why is Soil Contamination Harmful?
Contaminants are a concern because they can impact human health, biodiversity and the wider environment. For example, lead is recognised as a dangerous neurotoxin that can cause developmental delays in children and increase the risk of dementia in older people. Even small amounts of lead in our environment can be harmful to humans.
Do Contaminants Enter the Food You Grow?
Whether plants absorb heavy metals and other contaminants, and where those elements travel within plants, depends on the species. For example, leafy vegetables like spinach, lettuce and kale are particularly susceptible to absorbing lead and other toxins from the soil, while fruit trees may not be as susceptible. Trials at Delprat Garden in Newcastle have found that beans, watermelon, pumpkins and carrots accumulate toxins in the edible parts of the plant (fruit or roots). Sunflowers and mustard plants, however, accumulate lead and zinc in their roots but not in their leaves or flowers. Fig and tomato fruits in contaminated areas have been tested and found to contain no toxins.
The dangers are not just limited to direct ingestion of contaminated produce. When soil is disturbed through digging or weeding, pollutants can become airborne in dust and settle on other surfaces or be tracked into houses on the soles of shoes. Gardeners working the soil with bare hands can also encounter contaminants. Similarly, toxins can be ingested by children and pets who play in the garden or soil.
Is Your Soil Safe? Get a Test!
The first and most important step in relation to soil contamination is to know what’s in your soil. A professional soil test will reveal but can be costly. Fortunately, home gardeners in Australia can join citizen science efforts to map soil contamination and may be able to get a soil test done for free or the cost of a small donation:
- In Victoria, the EPA citizen science unit offers free soil tests through its GardenSafe program. Gardeners send up to three soil samples to GardenSafe and receive a report with information on soil nutrients and soil type as well as whether contaminants are present.
- Elsewhere in Australia gardeners can make a small donation ($20 is suggested) and receive a similar report from VegeSafe, which is associated with Macquarie University. (Note that this service is sometimes suspended due to a backlog of samples.)
Once you know what’s in your soil, you can make informed decisions about what to plant, what actions to take and whether remediation is necessary.
Gardening with Contaminated Soil
Discovering that your soil contains dangerous levels of heavy metals may be disheartening but it doesn’t need to mean an end to your gardening adventures. There are several simple steps that gardeners can take to reduce the impact of contaminated soil and grow healthy food:
- Raised garden beds: Raised garden beds are one of the most effective ways to avoid direct contact with contaminated soil. Fill your raised bed with purchased topsoil and you can then grow any type of edible crop including leafy greens.
- Mulch: Covering your soil with mulch limits soil disturbance and prevents soil sticking to your shoes and dust from spreading contaminants through the air.
- Don’t plant edibles under eaves: If you live in an older house that may have been painted with lead paint, avoid planting edibles under the dripline of eaves or directly beneath windowsills. It’s fine to plant ornamentals in these places.
- Provide safe play areas for children: install a sandpit or other play space where children can dig and play without coming into contact with your soil.
- Give chooks deep litter: make sure chickens can’t scratch in contaminated soil by installing a deep litter system that separates them and their food from the soil.
- Wear gloves and wash hands: wear gloves while gardening so your skin doesn’t come into direct contact with contaminated soil, and wash your hands after gardening.
- Wash veggies after harvesting: this will remove soil that may be attached to your crop before you consume it.
- Don’t wear shoes indoors: Contaminated soil (as well as dog poo and other nasties) can be carried indoors in the soles of shoes.
Phytoremediation: Nature’s Solution to Soil Contamination
One promising solution to soil contamination is phytoremediation, which is the use of plants to clean up polluted soils. Phytoremediation is seen as a better option than removing soil or capping it with a layer of clay. While these methods entail contaminants remaining in soil, phytoremediation has the ability to remove heavy metals from soils permanently.
Certain plant species have the ability to absorb contaminants from the soil. The toxins then accumulate in the plants’ tissues. As noted above, plants like sunflowers and mustard greens have been shown to absorb heavy metals such as lead, arsenic and cadmium. The plants can then be removed and composted in a dedicated compost heap. The question of how to dispose of the resultant compost, which has a smaller volume of plant matter but still contains heavy metals, is still being worked on. Delprat Garden in Newcastle is one site where research into phytoremediation is being done. You can see the results of their research here.
Urban gardening can be a fulfilling and sustainable way to grow your own food, but it’s essential to be aware of the risks associated with soil contamination. By testing your soil, choosing appropriate crops, and using some simple strategies, you can mitigate the dangers and create a healthier, more productive garden.
References:
- Gardensafe https://www.epa.vic.gov.au/for-community/get-involved/citizen-science-program/gardensafe/garden-safely-with-epa
- Vegesafe: https://www.360dustanalysis.com/pages/vegesafe-about
- Bulleen Art & Garden: Soil Contamination https://www.baag.com.au/soil-contamination/
- Gardening Australia, “Soil Safety” https://www.abc.net.au/gardening/how-to/soil-safety/103472326
- Gardening Australia, “Plants to the Rescue” https://www.abc.net.au/gardening/how-to/plants-to-the-rescue/102076168
- Taylor M and Filippelli G, 'Wearing shoes in the house is just plain gross. The verdict from scientists who study indoor contaminants' The Conversation 2022.
- Delprat Garden: https://delpratgarden.com.au/garden-performance
Soil contamination and safety in urban areas
For a deep-dive on this topic see our upcoming class
" This session was very informative, inspiring and helpful. I will be putting Craig's advice into practice!"
Brandon
Soil Compaction Masterclass
Netting Fruit Trees
If you're a gardener looking to protect your ripening fruit or berries from birds and other hungry wildlife, netting fruit trees can be a real lifesaver. Providing a physical barrier between your crop and animals, netting is an effective, chemical-free method of pest control. But netting also poses risks to the animals who share our gardens. Wildlife rescue services regularly report flying foxes, bats, birds and reptiles that have been injured or killed after becoming entangled in netting in suburban gardens.
Animals including birds, grey-headed flying foxes, blue tongue lizards and even snakes will all take an interest in fruit and berries, often before the fruit is considered ripe to human palates. Unfortunately, loosely installed netting or nets with holes, gaps or flaps can all snag animals’ wings, beaks or claws, and reptiles often try unsuccessfully to squeeze through the holes in the netting, leading to serious harm. When animals get tangled in netting, they often panic and can be injured more severely as the netting cuts into them as they struggle.
The good news is that gardeners can take a few simple precautions to protect their harvest without risk to wildlife.
When to use netting
Netting is most useful when your crops are at a vulnerable stage, particularly when fruit are ripening. Ideally, fruit trees should be netted for the shortest time possible; wait until fruit is close to mature size and showing signs of ripening before installing nets. Having said that, many gardeners will have experienced the disappointment of going to net their trees only to find the fruit has already been nibbled by unwelcome visitors, so don’t leave it too late either.
Wildlife friendly netting
While no netting can be considered 100% safe for wildlife, rescue organisations promote the following types of products to reduce the risk of entanglement. Guidelines for wildlife friendly netting are legislated in the ACT and Victoria, making it illegal to sell or use non-compliant products in those states.
Netting should be densely woven and have a mesh size of less than 5mm x 5mm when stretched. To test whether your netting meets this standard, see if you can poke your finger through the holes – if you can fit your fingers through, dispose of that product and purchase a ‘bird friendly’ or ‘wildlife friendly’ option. Note that this is a maximum mesh size, but smaller gauges are available and are even less likely to accidentally snare animals.
White nets are more visible to animals and are recommended over darker colours.
Picking the right netting
There are a few different types of netting to choose from, and each one has its pros and cons. Here’s a quick breakdown:
- Bird netting: This netting has the largest mesh size to keep birds and other large animals from your crop but allows pollinators in to do their work. It’s also the most economical choice for larger trees, but can be tricky to install as the large holes tend to snag on small branches.
- Insect exclusion netting: This netting has smaller holes (usually around 2mm) and is usually used to keep insects off veggies. Using insect exclusion netting to protect fruit may seem like overkill, however the finer mesh size makes the net less likely to snag on branches making it easier to install than bird netting. Note that the mesh size isn’t small enough to protect fruit from Qld fruit fly.
- Fruit protection bags and sleeves: Bags made from insect exclusion netting can be placed around individual fruit or clusters of fruit (like apples or peaches) or the sleeves can be used to protect single branches. While this option may not protect your entire harvest, the bags are easy to install and are a good option where trees are too large to net or where getting a partial harvest is OK.
- Sustainable alternatives: If you’re looking for something a little more eco-friendly you can repurpose items such as old net curtains or an op shop bridal veil, or use paper bags to protect individual fruit. They can work just as well as store-bought netting, and they’re often made of natural fibres, meaning that they’re compostable at the end of their life. Just make sure all parts of the fabric pass the 5mm x 5mm ‘finger test’ described above.
How to use netting safely
Netting fruit trees in the right way is as important as the type of netting you use. Here are a few tips:
- Make it taut: Loose netting is a big no-no. It can create gaps that allows animals to slip into the enclosure and they are more likely to become ensnared in areas of loose netting. Make sure the netting is taut and securely fastened when it is installed and retighten it when needed.
- Use a frame: A frame, whether purchased or DIY (using PVC pipes or a build-your-own kit) helps to keep tension in the netting and to keep it off the plants. This will prevent the netting from touching the fruit, ensuring its safe from being eaten (birds are able to suck ripe flesh through exclusion bags or netting, though they seem able to do this without damaging the fabric). Frames can be used over pots and raised garden beds as well as for trees grown in garden beds.
- Secure the bottom: Make sure the netting is secured at the bottom so animals can’t sneak under it and become trapped in the enclosure. There are two options: weighting or pegging the hem of the netting around the dripline of the tree, and gathering the netting snugly around the tree’s trunk and securing it with a tie.
- Use clips and ties: Bulldog clips or similar attached to the frame can help keep the netting taut, even during windy weather.
When installing netting remember that you will need access under it to harvest the fruit. Some nets are designed to allow this, with openings with overlapping pieces of netting or zips to provide easy access.
It’s worth noting that dwarf varieties of fruit trees are easier to net than full-size trees, that a well-pruned and maintained tree will be easier to net than a neglected one, and that trees grown in pots may need netting just the same as those grown in-ground.
Monitoring and maintenance
Netting fruit trees shouldn’t be a set and forget exercise. As well as regularly checking on the ripeness of the fruit, it’s important to check your netting regularly for trapped wildlife—ideally every morning and evening. Make sure the netting is taut and secure and that no birds, bats or reptiles are trapped in the mesh.
Small branches, wind-blown debris and insects can all get snagged in netting, sometimes creating rips or holes. These should be repaired as soon as possible. Do this by hand sewing the edges together while the net is on the tree or using a sewing machine on a wide zigzag setting at the end of the season.
End-of-life disposal
While plant-based, compostable netting is now available for purchase in Europe, in Australia we still rely on plastic for netting fruit trees. Maintaining your netting and repairing it when needed is a better option than treating it as an easily replaceable item. At the end of its life, dispose of netting responsibly so that it doesn’t pose an ongoing risk for wildlife, whether in your garden, in landfill or in waterways.
Netting is a fantastic way to protect your fruit trees from pests and wildlife, but it’s super important to use it in a way that’s safe for the animals around you. By choosing the right type of netting, making sure it’s securely fastened, and regularly checking for entangled wildlife, you can protect both your plants and the creatures that share your garden.
Managing Rats with IPM
“You dirty rat!” This phrase embodies the frustration many feel towards rats in the garden. These uninvited guests seem ever-present, scuttling along fences, digging under the compost heap and tasting our produce.
Addressing a rat problem does not always mean resorting to toxic baits. By using a more environmentally sustainable approach, rat populations can be managed without risking the health of the environment. This article explores methods of rat control based on the principles of Integrated Pest Management (IPM).
Why Are Rats a Problem?
Before diving into control methods, it is good to understand a little more about rats and why they make such pesky pests (apart from their appetite for your ripening tomatoes).
Rats are intelligent mammals that are capable of learning and problem solving. They are also fast and flexible movers, and are omnivores that aren’t fussy about their diet. These characteristics combine to make rats great survivors wherever they are found.
Rats breed quickly. They reach puberty at around 5 weeks old and females have a gestation period of only 3 weeks. Litters often include six to 12 young, and the breeding cycle can begin again within three or four days of the female rat giving birth. You do the maths – that’s a lot of rats!
Step One: Is It a Rat?
Rats around homes in urban areas are likely to be either Black Rats (Rattus rattus) or Brown Rats (Rattus norvegicus). Australia is also home to several species of native rat and other look-alikes, so its good to make sure you know who's taken up residence in your garden before beginning control measures.
The following characteristics should help you with an accurate ID:
Black Rat: Despite its name, the Black Rat has greyish-brown fur with a paler coloured belly and a tail longer than its body; its an excellent climber.
Brown Rat: This one does live up to its name, and has brown fur, again with a paler coloured belly. The tail is shorter than the body and Brown Rats are poor climbers, preferring to stay at ground level.
Bush Rat: A native species with charcoal to brown fur and rounded ears. The tail is shorter than the body. Bush rats are shy and unlikely to be found in inner urban areas.
Rakali (or Water Rat): A native with a large body up to 60cm long, prominent whiskers, webbed feet and a white-tipped tail. Rakali are active during the day and favour salt or freshwater swamps and shorelines.1
Antichinus: A small native marsupial with crinkled ears that look like two lobes per ear. Compared to rats' large front teeth, antichinus have several rows of small teeth. The tail is equal to or shorter than the body and they are good climbers.2
Using Integrated Pest Management (IPM)
IPM is a holistic approach that combines multiple strategies to manage pests. It requires an understanding of the pest's life cycle, behaviour and habitat, but allows gardeners to use a variety of control measures without resorting to harsh chemicals. According to the Food and Agriculture Organization (FAO), IPM can significantly reduce the need for chemical pesticides, providing a sustainable alternative for both home and commercial gardens.3
Like other rodents, rats thrive in environments that provide food, shelter and water. Thus, the first step in any pest management strategy is to assess these environmental factors. Identifying the causes of infestation can help determine the most effective management practices.4
Physical Controls
Trapping
Setting traps can be effective, though rats quickly learn to avoid them if they see the dead corpses of other rats nearby. Old-style snap traps, when placed in areas of high activity, can capture rats without the risks associated with poison. Traps that use compressed air to deliver a fatal blow or heavy-duty bands to strangle the rats are also available, as well as designs that trap the animals live.
Set traps carefully in a covered place away from children and pets. Despite what you’ve seen in cartoons, cheese is often not an effective lure; peanut butter, pumpkin seeds or meat are more appealing. Regularly checking and disposing of corpses or of live-trapped rats in a humane way is essential.
Physical Barriers
Placing bricks on the lids of compost bins or attaching wire mesh under them can prevent rats from accessing food scraps. Similarly, keep pet food in containers with secure, closable lids.6
Physical barriers can also be used to protect your ripening fruit and veggies. Fruit cages made from wire mesh with a small gauge, fruit bags made from flyscreen or shadecloth covers over veggie beds are effective. Netting, even when well secured at the base, often isn’t.
Raised garden beds with steel sides can also physically block rats by making it difficult for them to climb up to crops.
Cultural Controls
Garden Clean Up
One of the simplest and most effective strategies to avoid major problems with rats is to eliminate their nesting and hiding spots. Tidying the garden and removing debris such as large piles of leaves or abandoned building materials can reduce the nooks and crannies where rats hide and nest. Storing firewood off the ground also removes another potential nesting site. Inspect your house, garage and shed for access points, especially at ground level, and fill them or block access with wire mesh.
Food Management
As mentioned above, proper food storage is essential in preventing rats from being attracted to your garden. Feed pets only what they need and store pet food securely to remove food sources. If you have chooks, ensure that their feed is kept in rodent-proof containers and that scraps aren’t left on the ground overnight.
Plant Selection
Palm trees can be a favourite hideout for black rats, while native trees provide ideal habitat for native rat predators, including possums.
Biological Controls
Encouraging natural predators can be an effective biological control method. While introducing a cat into the garden is an age-old solution, it isn’t recommended because of the proven dangers to wildlife.5 Contrary to what many believe, powerful owls do not feed directly on rats. Possums do, however, so welcoming possums to your garden may be helpful.
Chemical Controls
Homemade Sprays
There is a long list of herbal and other scents said to deter rats. Though there is little evidence as to their effectiveness, gardeners could try homemade sprays containing peppermint oil, spearmint oil, camphor, cloves, garlic or chilli. Ammonia is also often listed, the theory being that it is similar in smell to cat urine.
Rodenticide Baits
While setting rat baits may appear to be an easy solution to your rat problem, the animals die in pain over a long period and the baits pose risks to non-target species as well as the wider environment. Anticoagulant rodenticides, the most commonly used type, work by preventing rats’ blood from clotting. After consuming a fatal dose of the bait, rats typically die 5 to 10 days later from internal bleeding or from cuts or scratches.7 During this time they become weak and slow-moving and may be eaten by pets or wildlife, or become roadkill.8,9 There is growing evidence that the chemicals in rat baits are harming wildlife including birds, mammals, reptiles and amphibians.
Rat baits come in several forms: blocks, pellets, gels, powders and pastes. Anticoagulant baits are generally divided into two types:
First Generation Anticoagulant Rodenticides (FGAR; products containing warfarin, pindone, chlorophaninone, diphacinone): Also called multi-dose anticoagulants, rats must feed more than once for the baits to be fatal. There is less chance of secondary poisoning occurring in non-target animals if they eat rats poisoned with an FGAR, but the rats themselves still die a slow and often painful death.
Second Generation Anticoagulant Rodenticides (SGAR; products containing difenacoum, brodifacoum, bromadiolone and difethialone): Rats can receive a fatal dose from one feed on SGARs, however they still die slowly. Because they often return to feed on the bait after the first feed, more toxins accumulate in their bodies and they therefore pose a greater risk of harm to non-target species. SGARs have been found not only in possums that feed on dead rats, but also further up the food chain. A 2022 survey of deceased powerful owls in Melbourne found SGARs were in 83.3% of the owls tested, even though powerful owls do not usually feed on rodents. The researchers concluded that the toxin had moved through the food chain from rats via possums to the owls.10
Non-anticoagulant rodenticides containing sodium chloride are also available and are promoted as a human and pet safe bait option. They kill rodents through dehydration. Rats must feed on the baits several times over 2-5 days, taking 3-7 days to die.
In summary, a holistic rat control program involving removing food and nesting sites, crop protection and some trapping can reduce the chances of a major rat infestation. This evidence-based approach not only protects your garden but also keeps harmful anticoagulants out of the food chain of our native animals.
References
- Connecting Country "Which Rat is That?"
- Australian Museum "Is it a Rat?"
- Food and Agriculture Organization (FAO). (2019). "Integrated Pest Management: A Sustainable Approach."
- Dreyer, K., et al. (2021). "Sustainable Pest Management: A Review of Integrated Approaches." Pest Management Science\, 77(3), 1145-1154.
- Baker, P. J., et al. (2020). "The Role of Cats in Managing Rodent Populations in Urban Areas." Urban Ecosystems, 23(1), 11-20.
- Morrison, R. A., et al. (2020). "Physical Barriers and Traps: Effective Strategies for Managing Rodent Pests." Journal of Pest Science, 93(2), 287-295.
- https://www.apvma.gov.au/resources/chemicals-news/rodenticides#what-is-an-anticoagulant-rodenticide-
- https://www.wires.org.au/wildlife-information/wildlife-and-pesticides
- Rattner, B. A., et al. (2020). "Risk of Secondary Poisoning in Non-target Species from Anticoagulant Rodenticides." Environmental Toxicology and Chemistry, 39(7), 1783-1791
- Cooke, R., et al. (2022), "Widespread exposure of powerful owls to second-generation anticoagulant rodenticides in Australia spans an urban to agricultural and forest landscape." Science of The Total Environment, 819, 2022,
- https://wildlifehealthaustralia.com.au/Portals/0/ResourceCentre/FactSheets/Multiple/Rodenticide_Toxicity_in_Australian_Wildlife.pdf
Pest Alert: Polyphagous Shot-Hole Borer (PSHB)
The Polyphagous shot-hole borer (known as PSHB; Euwallacea fornicates) is a pest first detected in Australia 2021 in metropolitan Perth. Native to Southeast Asia the small beetle, its tunnelling larvae and the fungus associated with it are damaging and invasive pest species. They have previously spread to Israel, the USA, South Africa and Argentina.
The PSHB’s arrival in Perth presents a new challenge for urban landscapes and home gardeners. As of September 2024, the borer was only known to be present in the Perth metropolitan area.
What Is a Borer?
A borer is the larvae of a small beetle or moth that lays its eggs on the bark or in the wood of trees. The larvae, which look like tiny grubs, chew on the wood of the tree. They create intricate tunnels within the tissue of the wood and make small exit holes in the trunk when they emerge as adult beetles.
Borers are often considered to be garden pests because their tunnelling can weaken branches and interrupt the flow of water and nutrients through the wood. In some cases this ringbarks and kills the tree. Borers tend to infest older trees or trees already weakened by other pests, diseases or unfavourable environmental conditions.
What makes the Polyphagous Shot-Hole Borer (PSHB) different?
While there are many species of borer present in Australia, the PSHB is receiving attention because it is considered highly invasive and damaging to both urban and agricultural trees. Left unchecked, the borer could seriously impact our urban tree canopy as well as important horticultural crops such as avocados and almonds.
One of the reasons that PSHB is of concern is that it uses a wide variety of trees – up to 400 species – as its host. Another is the borer’s symbiotic relationship with a Fusarium fungus, which it cultivates inside the host trees. This fungus serves as a food source for the beetle and its larvae, but while growing inside the tree it blocks the vascular tissue and movement of water and nutrients. This can lead to fusarium die back or death.
Identification
In its adult form, the PSHB is a small brown to black beetle, the females measuring approximately 2 mm in length and able to fly. Males are slightly smaller, about 1.6 mm long, and wingless. The 3-4mm long larvae are white and C-shaped with a reddish head.
It is more likely that gardeners will see damage to the tree from an infestation (see below) than see the pest itself.
Life Cycle
As with many insects, the lifecycle of the PSHB comprises several distinct stages: egg, larvae, pupae and adult. The female beetle lays eggs inside the tunnels within the tree. A few days later, the eggs hatch into larvae which feed on the Fusarium fungus cultivated by the beetles.
After several weeks of development, the larvae pupate within the tunnels, transforming into adult beetles. The flightless male beetles remain in the tunnels while the females are mobile and able to fly to find new mates and host trees. The entire life cycle from egg to adult can take six to eight weeks, depending on environmental conditions and the health of the host tree.
Host Trees
PSHB is known to infest over 500 tree species, with a particular affinity for box elder maples (Acer negundo). In Western Australia, the beetle has shown a preference for species including maple (Acer sp.), black locust (Robinia sp.), coral tree (Erythrina sp.), London plane tree (Platinus sp.) and fig (Ficus sp.) including Moreton Bay and Port Jackson figs. It also infests many species of fruit tree, including avocado, mango, citrus, carob, mulberry, macadamia, almond and loquat. This broad range of host species underscores the potentially serious impact to the urban tree canopy.
Signs of Infestation
Identifying PSHB infestations involves looking for specific symptoms on the bark of trees, rather than for the pests themselves. Symptoms include:
- Tiny exit holes (about 1 mm in diameter, about the size of the tip of a ballpoint pen) in tree trunks.
- Intricate galleries or tunnels in the wood, which look like cobwebs or leadlight patterns in cross-section.
- Frass or sawdust at the openings of the holes.
- Gumming, a thick resin or sap produced by the tree in response to damage.
- Lesions, staining or other discolouration in the wood
- Sugar volcanoes, a sugary substance exuded by the tree in response to damage by the borer
- Dieback of branches and leaves due to the Fusarium fungus.
Management Strategies
In response to the threat posed by PSHB, a quarantine area was extended across the entire Perth metropolitan area in September 2024 after the borers spread beyond the initial, smaller quarantine zone. The larger quarantine region includes 30 local government areas and imposes restrictions on the movement of timber, plant material and wood processing machinery, while also focusing on surveillance and monitoring.
Effective management of PSHB relies on early detection and preventive measures:
- Trapping: Yellow sticky traps with pheromone lures are used to monitor beetle activity by attracting and capturing PSHB beetles.
- Reporting: If you suspect a PSHB infestation, report it to the DPIRD Pest and Disease Information Service at +61 (0)8 9368 3080 or via email at padis@dpird.wa.gov.au. You can also use the MyPestGuide® Reporter app for reporting.
- Pruning and Removal: Infested trees may need to be pruned or removed completely.
- Preventive Practices: To avoid spreading PSHB, it's essential to clean and disinfect pruning tools and machinery and avoid moving trees or plant material from infested areas.
Home gardeners can help by monitoring their trees for symptoms of PSHB, focusing on the general health of the trees in their gardens, and using mulch made from grass clippings or compost rather than wood chips. Observe the restrictions on moving plant material and machinery beyond the boundaries of the quarantine zone.
Planting native species less attractive to PSHB can also help manage the spread. Recommended plants include the WA Peppermint Tree (Agonis flexuosa), Sydney Red Gum (Angophora costata), various palms and other ornamental species. For more detailed planting recommendations, refer to this planting guide.
Should Gardeners Outside Perth be Worried?
Gardeners in the areas where PSHB is known to occur should follow all recommendations in relation to suspected infestations. Of course, no one likes to see trees in their neighbourhood hard pruned or removed, however left unchecked this pest represents a major threat to our urban trees.
For gardening professionals and home gardeners in the rest of Australia, being aware of this new species and the symptoms to look out for is all that’s required at present.
References
All images courtesy of WA DBIRD
Australian Government Outbreak: Animal and Plant Pests and Diseases
WA Department of Industries and Regional Development
Paap, Z.W. De Beer, D. Migliorini, W.J. Nel, M.J. Wingfield (2018) First report of the polyphagous shothole borer (PHSB) and its fungal symbiont in South Africa, South African Journal of Botany, Vol 115, p 305.
Gardening Australia 'Polyphagous Shot-Hole Borer'
Water Management Techniques for Climate-Resilient Gardens
Australia's rainfall patterns are undergoing significant changes as a result of climate change, manifesting in increasingly erratic and extreme weather events. Australia is now experiencing more frequent and severe droughts, intensified by reduced rainfall in key regions. Conversely, some regions are facing increased rainfall and a heightened risk of intense flooding.
This shift in weather patterns has profound implications for home gardeners. Efficient use and conservation of water resources is now paramount for sustaining a healthy garden.
Using Water Efficiently
Rainwater Harvesting
One of the most effective water management techniques is rainwater harvesting. Installing rain barrels or larger rainwater tanks can capture and store runoff from rooftops, providing a sustainable water source during dry periods. Filtered rainwater is ideal to use to water gardens as it is free from the salts and chemicals often found in tap water, which can build up in the soil and harm plants over time.
Efficient Watering: Drip Irrigation
Drip irrigation systems are highly efficient for watering plants directly at the root level, minimising water waste through evaporation and runoff. Drip systems deliver water slowly and consistently, ensuring that plants receive the moisture they need without oversaturation. Additionally, drip irrigation can be automated with timers, allowing for precise control over watering schedules and further conserving water.
Mulching
Mulching is another essential practice for conserving soil moisture. Organic mulches, such as lucerne, wood chips or compost, create a protective layer over the soil, reducing evaporation, moderating soil temperature and suppressing weeds. As mulch breaks down, it also adds valuable organic matter to the soil, enhancing its structure and fertility.
Greywater Systems
Incorporating greywater systems into your garden design can further enhance water efficiency. Greywater is wastewater from household sources like sinks, showers and washing machines. When properly treated, greywater can be reused for irrigation, reducing the demand on freshwater resources. Greywater systems must be designed and installed carefully to ensure they are safe and compliant with local regulations.
Drought-Resistant Planting Zones
Creating drought-resistant planting zones within the garden is a strategic approach to water management. Grouping plants with similar water needs together allows for more efficient watering. Drought-tolerant plants, which have adapted to survive with minimal water, should be prioritised in areas that receive less irrigation. Examples of drought-tolerant plants include many native Australian species like kangaroo paw, grevillea, and banksia.
Preparing Your Garden for Heavy Rain Events
Heavy rain events can cause waterlogging and localised flooding in gardens. While rainwater tanks and good stormwater systems can help to contain and direct some rainfall, extreme rain events often dump excess water on gardens. Gardens with heathy soil, mulch and good drainage will help to slow down and soak up excess water as it travels across the garden.
Drainage and Healthy Soil
Soil drainage is crucial in preparing for heavy rain events because it helps manage the volume of water that infiltrates the soil and reduces the risk of waterlogging. Well-draining soil allows excess water to move through the ground rather than pooling on the surface, which can suffocate plant roots and lead to root rot. To improve soil drainage, incorporating organic materials like compost or aged manure can enhance soil structure, increasing its ability to absorb and retain water without becoming saturated. Raised garden beds or mounds can further assist by elevating plant roots above areas prone to standing water, ensuring that plants remain healthy and productive despite heavy rainfall. Effective soil drainage not only protects plants but also prevents water from causing soil erosion and damaging garden infrastructure.
Mulch and Heavy Rain
Mulch plays a vital role in preventing runoff and erosion, acting as a protective layer on the soil surface. By covering the soil with mulch, you create a barrier that reduces the initial impact of rainfall. This helps to slow down the rate at which water flows across the soil and decreases the likelihood of erosion.
Using Contours and Swales
Contour gardening involves shaping the land to follow the natural topography, which helps manage water flow and prevent erosion. Swales, or shallow, vegetated channels, can be incorporated into the garden design to capture and slow down rainwater runoff. This technique allows water to infiltrate the soil gradually, reducing erosion and improving groundwater recharge.
Engaging with the Community
Building a climate-resilient garden is not just an individual effort; it can also involve engaging with the broader gardening community. Joining local gardening groups, attending workshops, and participating in community gardening projects can provide valuable knowledge and support. Sharing experiences and tips with fellow gardeners can lead to innovative solutions and foster a sense of community resilience in the face of climate change.
For more detailed information on these practices and to connect with other passionate gardeners, purchase your tickets here and join SGA’s Climate Resilient Gardening Forum on Wednesday, 14th August 2024.
Cover Crops 101: The Key to Building Soil Health
Cover crops, also known as green manure, are plants grown primarily to benefit the soil rather than for harvest. These crops play a crucial role in sustainable gardening by improving soil structure, increasing organic matter, enhancing nutrient availability, and fostering beneficial soil microorganisms. Common cover crops include legumes (like clover and vetch), grasses (like rye and barley), and brassicas (like mustard).
The Benefits of Cover Crops
Enhancing Soil Structure
Cover crops improve soil structure by promoting the development of soil aggregates, which are clumps of soil particles held together by organic matter. This enhances water infiltration, reduces erosion, and creates a more aerated and stable soil environment. The deep roots of cover crops penetrate compacted soil layers, breaking them up and allowing for better root growth of subsequent crops. For example Tillage radish (Raphanus sativus), known for its deep taproots, breaks up compacted soil, which subsequent crops like corn and tomatoes benefit from.
Increasing Organic Matter
As cover crops grow, they add organic matter to the soil through their root systems and when they are eventually incorporated back into the soil. This organic matter is a vital component of healthy soil, improving its ability to retain moisture and nutrients. Over time, this increased biomass leads to more resilient and productive soil.
Enhancing Nutrient Availability
One of the most significant benefits of cover crops is their ability to fix nitrogen in the soil. Leguminous cover crops, such as clover and vetch, have a symbiotic relationship with nitrogen-fixing bacteria. These bacteria convert atmospheric nitrogen into a form that plants can use. When the cover crops are turned into the soil, they release this nitrogen, making it available for future crops. This natural fertilisation process reduces the need for synthetic fertilisers, promoting a more sustainable gardening approach.
Fostering Beneficial Soil Microorganisms
Cover crops such as Rye (Secale cereale) create a conducive environment for beneficial soil microorganisms, including fungi and bacteria. These microorganisms play a crucial role in nutrient cycling, organic matter decomposition, and disease suppression. Mycorrhizal fungi, for instance, form symbiotic relationships with plant roots, enhancing nutrient uptake and improving plant health.
Suppressing Weeds and Pests
Cover crops act as a living mulch, suppressing weed growth by outcompeting them for light, water, and nutrients. Additionally, some cover crops, like mustard, release bioactive compounds that can suppress soil-borne pests and diseases. This natural form of pest and weed control reduces the need for chemical interventions, promoting a healthier garden ecosystem. While companion plants such as lettuce and spinach enjoy reduced pest pressure and healthier growth.
Protecting Soil from Erosion
The dense growth of cover crops protects the soil surface from erosion caused by wind and water. Their root systems help to bind the soil particles together, preventing the loss of topsoil and maintaining soil fertility. This is particularly important in areas prone to heavy rains or strong winds.
How Cover Crops Create Living Soil
Living soil is a dynamic ecosystem teeming with beneficial microorganisms, insects, and earthworms. Cover crops play a crucial role in creating and maintaining this vibrant soil life. As cover crops grow, their roots exude organic compounds that feed soil microorganisms. These microorganisms, in turn, break down organic matter, releasing nutrients and enhancing soil fertility. The presence of a diverse and active soil biota improves soil structure, nutrient cycling, and overall plant health.
Incorporating cover crops into your gardening practices is a scientifically backed method for enhancing soil health and promoting sustainable gardening. Understanding the specific needs of your garden and choosing the right cover crops can lead to a thriving, nutrient-rich environment that supports robust plant growth. As gardeners, our goal should be to create living soil, teeming with life and capable of sustaining our plants in the most natural and efficient way possible. Embrace the power of cover crops and watch your garden flourish like never before.
Companion Planting
Heard about companion planting but don’t know what it is or where to start? This video explores how to use companion plants to improve the health and productivity of your garden; with a focus on using companion plants as decoys, camouflage, pest repellents and disease suppressants.
Learn what you should pair and grow together in your garden as well as tips on what you shouldn't pair. This video also examines how companion plants can provide a new food source.
Friends of SGA can enjoy exclusive access to this recording until the end of August.
For more information on companion planting see our article Companion Planting.
Citizen Science: A Pathway to Gardening Success and Biodiversity Conservation
In recent years, the realm of science has experienced a remarkable transformation, one that invites people from all walks of life to participate actively in the pursuit of knowledge. This movement, known as citizen science, empowers individuals to contribute valuable data and insights to scientific research, often through simple yet meaningful tasks.
While citizen science has deep historical roots, modern platforms like iNaturalist have revolutionized the accessibility and impact of this approach. In its essence, citizen science in the garden is an approach that harnesses the passion and knowledge of everyday individuals to observe and record nature to help gardeners make informed gardening decisions that foster ecological harmony.
Gardening is about more than just planting seeds and tending to crops; it's about cultivating a deeper connection with the natural world. By engaging in citizen science initiatives, gardeners can take this connection to new heights, contributing to scientific research while learning about the intricacies of and building their own biodiverse and resilient garden ecosystem.
One of the most exciting aspects of citizen science in the garden is its potential to shed light on the relationships between plants, insects, and other organisms. Through projects such as monitoring pollinator activity or tracking bird populations, gardeners can gather valuable data that helps scientists better understand local ecosystems and inform conservation efforts.
The strength of collective wisdom is undeniable. Being intricately connected to their local outdoors, gardeners involvement in building this wisdom and contributing to citizen science is significant. Enthusiasts intrigued by frogs and their potential presence in gardens are eagerly joining the "FrogID Australian Museum," app. This is an engaging citizen science project dedicated to monitoring frog populations in people's backyards and local communities. Participants contribute valuable data to aid researchers in better understanding frog habitats, behaviours, and population trends. FrogID also plays a crucial role in tracking the locations of Cane Toads and identifying areas where frogs thrive or face challenges. By correlating frog calls with weather patterns and habitat conditions, researchers gain insights into how different frog species adapt to a changing environment. Hop on board and be a part of this important research effort!
Citizen science apps are a great way to engage younger people in understanding and connecting to the natural world. The City Nature Challenge in April presents an opportunity for urban gardeners to engage in citizen science. This global event encourages people to explore and document the biodiversity in their cities using the iNaturalist app. By participating, gardeners can contribute valuable data about urban biodiversity whilst discovering the natural wonders hidden in their own neighbourhoods.
These projects not only benefit scientific research but also provide valuable insights for home gardeners. By learning about the flora and fauna in their area, gardeners can make informed decisions about plant selection and garden design, creating habitats that support local biodiversity and promote ecosystem resilience.
Furthermore, citizen science initiatives often provide opportunities for collaboration and community building. By connecting with fellow gardeners and scientists through online platforms or local events, participants can share knowledge, exchange ideas, and inspire one another to take their gardening efforts to new heights. Moreover, these activities often lead to collaboration and community building, whether through online platforms or local events.
Citizen science holds tremendous potential to revolutionise the way we approach gardening and biodiversity conservation. By engaging in simple yet impactful activities, like the Aussie Bird Count, gardeners can contribute to scientific research, deepen their connection with nature, and foster a sense of community among fellow enthusiasts (citizen scientists). And with these activities being great for the whole family, it’s an ideal way to involve children in exploring and learning about the wonders of the natural world - so don't forget to get the little people in your life involved, too!!
Learn more about becoming a citizen scientist, projects and groups you can join, and how to organise your own BioBlitz here.
Wildflower gardens – What’s the buzz about?
In the quest for sustainable and environmentally conscious practices, gardening enthusiasts and nature lovers alike are turning to a time-tested technique: wildflower gardening. In this article, Dr Lena Alice Schmidt, pollination biologist and director at Buzz Ecology, delves into the intricate world of cultivating biodiversity through wildflower gardens in Australia.
Key points
- Vibrant wildflower gardens comprising native plant species with a variety of flower colours, flower shapes and flowering times attract a wide range of native insects, which rely on the floral resources provided (i.e. nectar and pollen) for their development and health.
- The total number of bee species in Australia is estimated to be 2000, while other insects, such as flies, hoverflies, moths, butterflies, wasps and ants, also provide important pollination services to both wild plants and food crops.
- Local plant species that are long-lived and flower at different times of the year are well adapted to the local environment and provide native fauna with resources year-round, making them low-maintenance choices for your garden while supporting biodiversity.
Pollination by insects is a critical ecosystem service for many Australian native plants and contributes to crop production; however, many populations of wild bees and other insects are in decline. There is a sheer diversity of insects – including native bees, flies, hoverflies, moths, ants and wasps – which deliver pollination services. While they move pollen between flowers, insects visit flowers primarily to forage for nectar or pollen. Nectar contains carbohydrates which are important for insect flight, while pollen provides protein and other minerals which promote growth and development.
Different insect groups have different nutritional requirements.
While bees forage for both nectar and pollen, pure nectar feeders include butterflies and moths, which consequently prefer flowers with higher quantities of nectar. Nectar and pollen vary in quantity and composition across plant species, so do flower colour, shape and scent. These are all traits that have evolved to entice insects (and other fauna) to visit flowers and pollinate them for the plant to be able to reproduce.
Locally-adapted plant species are more likely to provide suitable flowers
and resources to the local insects.
From the insect perspective, many of our native pollinators have co-evolved with certain plant species and as such have innate preferences for flowers with specific colours, shapes or smells. The shape of the flower can restrict access to pollen and nectar; tubular flowers, for example, only offer resources to long-tongued insects like blue-banded bees (Amegilla spp.). If your wildflower garden consists of a variety of local plant species you are providing dietary diversity to the local insect community.
Native insects need a varied diet continuously throughout the year to keep buzzing.
Particularly in landscapes lacking in numbers and varieties of plant species due to landscape simplification and loss of natural habitats, insects can struggle to find adequate floral resources year-round. Additionally, more frequent bushfires combined with widespread drought can further reduce floral resource availability in native habitats. Planting a range of locally sourced, native plant species that are predominantly perennial and thus long-lived and flower at different times of the year can fill resource gaps. Plants that are normally found in the area are also better adapted to survive and thrive under the climate conditions experienced in our local landscapes and can persist for longer without needing to be re-established.
Wildflower gardens consisting of different vegetation layers (i.e. herbs, bushes, trees) can not only offer diverse floral resources, but also provide insects and other native fauna with sites for nesting and resting, supporting biodiversity and your local ecosystem.
If you are keen to create a wildflower garden for native bees and other insects, read more here:
https://www.researchgate.net/publication/347561274_Keeping_our_wild_pollinators_buzzing
Article and photographs copyright to Lena Alice Schmidt.
Thriving in the Heat: Managing Plant Heat Stress
As the mercury rises, your garden confronts the challenge of heat stress. Understanding how various plants respond to heat and employing appropriate strategies to shield them from excessive temperatures are essential for ensuring their well-being. Heat stress often leads to wilting, particularly in leafy greens like lettuce and spinach. To counter this, provide shade during the hottest parts of the day and ensure consistent watering. For fruits like tomatoes, excessive heat can affect fruit setting, so consider mulching to regulate soil temperature. Embrace heat-tolerant varieties, and prep your garden by adding organic matter to the soil to improve water retention.
Signs of heat stress include:
- Leaf Curling: Look for wilting or curling leaves, especially on the edges, which is a common indicator of heat stress.
- Discoloration: Changes in leaf colour, such as browning or yellowing, may signal that the plants are struggling with excessive heat.
- Stunted Growth: If your plants are not reaching their expected height or appear smaller than usual, it could be a response to heat stress.
Mitigating Heat Stress:
- Mulching: Apply a layer of organic mulch around plants to retain soil moisture, regulate temperature, and suppress weeds.
- Proper Watering: Water deeply and consistently, preferably in the early morning or late evening, to minimise water loss and support plant hydration. Introducing wicking beds can be instrumental in maintaining a readily available water supply.
- Shade Structures: Install shade cloth or create natural shading with taller plants to protect vulnerable crops from direct sunlight during peak hours.
- Soil Moisture Management: Use soil moisture meters to monitor moisture levels and avoid overwatering or underwatering.
- Incorporating perennials: Consider incorporating perennials into your summer garden for a resilient and thriving landscape. Unlike annuals, perennials boast more established root systems, offering increased resilience during the heat. These well-rooted plants can better withstand water stress, making them ideal for maintaining garden vibrancy through the hottest months.
By recognising the signs of heat stress and implementing effective solutions like mulching and shade provision, you can keep your summer garden looking lush. Experiment with diverse heat-resistant crops, such as capsicum, sweet potatoes, okra, and zucchini, to create a productive garden that withstands the challenges of summer.
The Importance of building soil health for a biodiverse, productive garden
Creating a thriving garden that not only sustains itself but also contributes to the broader ecosystem requires more than just sunlight and water. The secret to a successful, biodiverse, and highly productive garden lies beneath the surface – in the health of your soil. In this article, we'll explore the crucial role of soil health in fostering biodiversity and ensuring the productivity of your garden.
Nutrient-rich soil nurtures healthy plants
Soil serves as the primary source of nutrients for plants. A well-balanced, nutrient-rich soil provides plants with the essential elements they need to grow and produce. Adequate levels of nitrogen, phosphorus, potassium, and other micronutrients are vital for plant health. When soil health is optimised, plants are better equipped to resist pests and diseases, resulting in a more robust and productive garden. For instance, adding compost or well-rotted manure can significantly enhance soil structure and fertility, providing a steady supply of nutrients to your plants. Regular soil testing can also help you identify nutrient deficiencies and address them promptly.
Microbial activity enhances soil fertility
Healthy soil is teeming with microbial life, including bacteria, fungi, and other microorganisms. These tiny organisms play a crucial role in breaking down organic matter, releasing nutrients, and improving soil structure. Beneficial microbes form symbiotic relationships with plant roots, aiding in nutrient absorption and disease prevention. To foster microbial activity, consider incorporating good quality amendments like compost tea or worm castings into your soil. These amendments boost microbial populations, enhancing nutrient cycling and soil fertility.
Soil structure affects water retention and drainage
A well-structured soil with a good balance of sand, silt, and clay particles allows for optimal water retention and drainage. Building soil organic matter through the addition of amendments such as compost and other organic materials to enhance soil structure, promote aeration and create an environment where plant roots can thrive. Mulching with organic materials such as straw or wood chips helps maintain soil moisture and temperature, and will also break down to build your soil up with organic matter. A good way to evaluate this soil quality is to simply test how long the water lasts after a good soaking. Does your soil hold onto water (nutrients and other resources) like a sponge?
Biodiversity in the soil supports plant diversity
The health of your garden extends beyond what meets the eye. A diverse community of soil-dwelling organisms contributes to a balanced ecosystem. Earthworms, insects, and other invertebrates aerate the soil, break down organic matter, and contribute to nutrient cycling. Encouraging biodiversity in your soil can be as simple as rotating crops, planting cover crops, and reducing tillage. These practices support a variety of soil organisms, which in turn support a wide range of plant species in your garden.
Reducing the need for chemical inputs
A robust soil ecosystem can naturally suppress pests and diseases, reducing the reliance on synthetic pesticides and fertilisers. When soil health is prioritised, the garden becomes more resilient, and the need for chemical interventions decreases. This not only benefits the environment but also promotes the long-term sustainability of your garden. For example, introducing beneficial insects or using natural pest control methods can complement the soil’s natural defenses, creating a healthier and more balanced garden ecosystem.
Conclusion
In the world of gardening, healthy soil is the unsung. By prioritising soil health, gardeners can create a self-sustaining ecosystem that fosters biodiversity, supports plant growth, and yields abundant harvests. Building soil health is an investment in the long-term vitality of your garden, offering benefits that extend far beyond the surface. So, dig in, nurture your soil, and watch as your garden flourishes.
Cultivating Biodiversity: Wildflower Gardening
As we become increasingly aware of the importance of preserving our natural ecosystems, one simple and powerful way to make a positive impact is by planting native flowers in your garden. Australia, with its unique and diverse range of flora and fauna, offers an ideal setting for wildflower gardening. This article explores the numerous benefits of wildflower gardening and how it can support native insects to create a thriving and sustainable local ecosystem.
The Case for Wildflower Gardens
Australia's rich flora and fauna make it an ideal canvas for wildflower gardening. Here are a few reasons why you should consider planting native Australian wildflowers.
Fostering Biodiversity
Native flowers are a potent tool to nurture biodiversity in your vicinity. A mix of flowering plants accommodates a diverse range of native insects, ensuring a year-round haven for them.
Essential Pollinators
Native insects, including bees, flies, wasps, and even ants, play a critical role in pollination. By creating a thriving habitat for these crucial species, you enable the reproduction of countless plant species. At the same time, it increases the yields of your home-grown produce. From the delicious fruits and vegetables in your garden to the beautiful flowers adorning your landscape, insect pollinators are the unsung heroes behind a bountiful harvest.
Natural Pest Control
In addition to pollination, native insects also offer valuable pest control services. They prey on harmful insects that might otherwise damage your garden and crops. This natural form of pest control reduces the need for chemical pesticides.
Low-Maintenance Choices
Native flowering species are well-adapted to the local climate and soil conditions, making them low-maintenance choices for your garden. They have evolved to thrive in Australia's specific environmental conditions, reducing the need for excessive watering and fertiliser. This helps save time, effort, and money.
Enjoying the Beauty of Native Flora
In addition to their ecological benefits, native flowers offer a stunning array of colours and shapes that can transform your garden into a vibrant and beautiful space.
Growing Your Wildflower Garden: A Short Planting Guide
Kickstart a wildflower garden with this list of native Australian wildflowers that you can use to attract native insects to your garden, along with the insects they can attract and their benefits:
Billy Buttons (Craspedia spp.)
- Attracts: Native bees and butterflies.
- Benefits: Billy Buttons produce vibrant yellow spherical flowers that provide nectar for native bees and are a food source for butterflies.
Kangaroo Grass (Themeda triandra)
- Attracts: Native grasshoppers and caterpillars.
- Benefits: Kangaroo Grass serves as a host plant for various native insects, making it an essential component of a balanced ecosystem.
Common Everlasting (Chrysocephalum apiculatum)
- Attracts: Native bees, butterflies, and moths.
- Benefits: The yellow flowers of this perennial attract a range of pollinators, while the foliage provides habitat for small insects.
Bush Pea (Pultenaea spp.)
- Attracts: Native bees, beetles, flies, and hoverflies.
- Benefits: Bush Pea plants have bright yellow or red flowers that are a nectar and pollen source for native bees and other pollinators, supporting biodiversity in your garden.
Mulla Mulla (Ptilotus spp.)
- Attracts: Native bees, butterflies, wasps, moths, and bee flies.
- Benefits: The unique cylindrical flowers of Mulla Mulla are an excellent nectar source for native bees and a striking addition to your garden.
Geraldton Wax (Chamelaucium uncinatum)
- Attracts: Native bees, flies, beetles, and honeyeaters.
- Benefits: The fragrant flowers of Geraldton Wax attract native bees and nectar-feeding birds, contributing to pollination and local bird diversity.
Hakea (Hakea spp.)
- Attracts: Native bees, moths, ants, wasps, beetles, small marsupials, and honeyeaters.
- Benefits: Hakea plants produce nectar- and pollen-rich flowers, making them a valuable resource for native bees and butterflies in your garden.
Dampiera (Dampiera spp.)
- Attracts: Native bees, hoverflies, and small native wasps.
- Benefits: Dampiera's vibrant blue or purple flowers provide nectar for native bees and offer nesting sites for small wasps.
Emu Bush (Eremophila spp.)
- Attracts: Native bees and honeyeaters.
- Benefits: Emu Bush is well-known for its tubular flowers, attracting various pollinators, particularly native bees and nectar-feeding birds.
Daisy Bush (Olearia spp.)
- Attracts: Native bees, hoverflies, beetles, flies, moths, and butterflies.
- BeDiscover Wildflower Gardening: Attract native insects and reap the rewards: Daisy Bush, with its white or pink daisy-like flowers, provides nectar and pollen for native bees and a food source for butterflies.
These native wildflowers offer a diverse range of colours, shapes, and sizes to enhance the beauty of your garden while supporting local ecosystems. By planting these species, you will provide food and habitat for a wide array of native insects, contributing to the health of your garden and the broader Australian environment. Win-win.
No Mow Lawn
Traditional lawns, often characterised by their lush, manicured appearance, have long been the norm in Australian landscaping. However, an exciting and eco-conscious alternative is gaining traction across the country – the no mow lawn. These natural, wilder landscapes have numerous benefits that go far beyond aesthetics, making them a compelling choice for environmentally conscious homeowners. In this article, we explore the advantages of embracing a no mow lawn in Australia.
Biodiversity Boost
One 
of the most compelling benefits of a no mow lawn is the promotion of biodiversity. Traditional lawns, with their uniform grass species, offer limited habitat and forage opportunities for local wildlife. In contrast, no mow lawns feature a diverse mix of native grasses, wildflowers, and other plants that attract pollinators, birds, and insects. This thriving ecosystem can help support local wildlife populations and even contribute to the protection of endangered species.
Water Conservation
Australia's climate is often characterised by periods of drought and water scarcity. Maintaining a traditional lawn can be water-intensive, as it requires frequent irrigation to stay green and lush. No mow lawns, once established, are generally more drought-resistant and can thrive with minimal watering, reducing the strain on precious water resources.
Low Maintenance
No mow lawns are aptly named for their minimal maintenance requirements. Unlike traditional lawns that necessitate regular mowing, fertilising, and herbicide use, these natural landscapes thrive with little intervention. This not only saves homeowners time and effort but also reduces the need for harmful chemicals and emissions associated with lawn maintenance equipment.
Soil Health
The continuous mowing of traditional lawns can lead to soil compaction and degradation. In contrast, no mow lawns encourage healthy soil ecosystems. The presence of native plants and deep-rooted grasses in no mow lawns can improve soil structure, increase nutrient cycling, and enhance water infiltration. This, in turn, helps combat erosion and fosters a more resilient landscape.
Aesthetic Appeal
No mow lawns have a unique and natural beauty that can enhance the overall aesthetics of your property. The varied colours, textures, and heights of the plants provide year-round visual interest, with seasonal blooms adding bursts of color. Moreover, these landscapes can offer a tranquil and calming environment, perfect for relaxation and contemplation.
Conclusion
Embracing a no mow lawn in Australia is not just a landscaping choice; it's a commitment to environmental stewardship. These wilder, more natural landscapes offer a multitude of benefits, from promoting biodiversity and conserving water to reducing maintenance and enhancing soil health. As climate change and environmental concerns continue to rise, choosing a no mow lawn becomes a meaningful and sustainable way to contribute to a greener, healthier future for both your property and the planet. So, why not consider joining the green revolution and letting your lawn go wild?
Weed Control
Several different approaches are needed for weed control since eradication is difficult and can be expensive. Preventing weeds from establishing and early intervention is much easier and much cheaper. Let’s look at approaches to weed management which begins with prevention.
It is best to identify the target weeds. By doing this the method for control can be more specific and potentially much more effective. Know whether the weeds are annual or perennial and how they spread, such as by seed or by underground plant parts.
While there are plants that are formally classified as weeds, there are others that are common garden plants that we may regard as weeds because of their invasive nature e.g. violets and the Australian native plant Dichondra. In some circumstances they are lovely, but not so in others.
Prevention
- Check through the plants you already have in your garden and make sure they are not weedy
- Remove any weedy plants from your garden
- Be careful about disposal of plant material/green waste - if removing weedy material it can be left in a plastic bag in the sun - effectively cooking (solarising) them before disposal.
- Minimise disturbance of soil to decrease the opportunities for weed seed to reach the surface and germinate (e.g. No Dig gardening)
- Choose plants that are not likely to become weedy in your area
- Always work from areas of low infestation of weeds to more infested areas because:
- It is quicker and easier to start with and should be able to achieve canopy cover more quickly to reduce further weed growth.
- this minimises disturbance in the least disturbed areas and avoids taking more weeds/seed from the worse areas into areas with lesser weed growth.
- Avoid unnecessary fertilising which can favour weeds. Often weed species grow quickly utilising available resources better than chosen landscape species so they can out-compete them in some circumstances
- Prevent weeds from being imported to your site/garden by choosing weed-free plants from the nursery. Remove any weeds that might germinate in the top layer of the planting medium.
- Seeds can persist in soil for a very long time. Minimise disturbance of soil to decrease the opportunities for weed seed to reach the surface and germinate (eg. No-dig gardening)
Suppression
- Competition - Select vigorous plant species to cover open ground. This shades/prevents light from reaching soil and allowing germination of weed seed.
- Mulch - Suppress weeds by preventing light from reaching seeds. This prevents germination or causes the seed to use up reserves trying to reach surface. Mulch has additional benefits of reducing evaporation from soil and captures rainfall, as well as its potential aesthetic value.
Sheet mulches: They must be kept in good condition. However, this can reduce the ability for water and oxygen to reach the soil dependent on mulch used.- Granular mulches: Should be 75-100mm deep and coarse in texture. Thicker than 100mm reduces the ability of oxygen and water to get into the soil. Mulch can potentially increase frost damage to plants by preventing soil from warming. Carbon-rich mulches can cause a temporary reduction in soil nitrogen as soil microbes use it to break down the mulch.
| Organic | Inorganic | |
| Sheet Mulch | Paper, cardboard, jute | Old carpet, plastic film, weed mat, woven plastic |
| Granular Mulch | Bark, wood chips, straw, recycled Timber, hay, leaves, grass clippings, compost | pebbles, rocks, crushed bricks, |
Eradication/removal
Control existing weeds around the garden regularly to reduce weed seed build up i.e. cut down or pull weeds before they flower and can produce seed.
Manual
This involves removal by hand or hand-held tools such as a hoe, fork or spade.
It is a highly selective method and very useful on small scale or in very high value landscapes. It is most effective on annual weeds but not as effective on perennial weeds that regrow from fragments left behind. It is a labour-intensive strategy.
- Weed Pulling Technique - This method is partly dependent on root systems of weeds. Initial pulling of the weed must be gentle and tentative to establish how firmly the plant is rooted, being careful not to break the roots.
- Use a gentle steady movement and pull in the direction of the root growth (which is the line of least resistance).
- Wedge a weed knife or trowel into the soil under a weed at an angle of approximately 45deg. Hold the top section of the weed taut and then use the tool to lever the weed out.
Tools for Hand Weeding
- Short handled such as trowel, hand fork, hand hoes, hori-hori Japanese garden knife or hand weeder tools which come in a variety of shapes, sizes and weights for either cutting or levering out weeds.
- Long handled such as a Dutch hoe and a range of push-pull hoes for slicing weeds off just under the surface of the soil. This works best for annual weeds or weeds that do not regrow from underground parts.
- Tree Poppers - for removal of woody weeds with stem diameters of up to 60mm.
Girdling or Ringbarking
This is suitable for large woody weeds or weedy trees and involves cutting several centimetres of bark from the entire circumference of the weed or tree. This prevents the upwards flow of water and nutrients from the roots of a plant to the canopy. It also stops the flow of sugars, the products of photosynthesis, from reaching the roots effectively starving the weed and causing it to die.
Mechanical Cultivation (tillage)
This method uses powered devices (eg. rotary hoe or tractor) and can chop up and bury weeds. It is of most use for site preparation and pre-planting. Can cause structural damage to the soil and may damage roots of non-target plants.
Thermal Treatment
All such approaches require repeated treatments at varying intervals in order to keep weed density at an acceptable level. The frequency of treatment depends on weed species, initial weed cover/density, climate, type of soil surface. It may involve up to 11-12 treatments per year to control weeds to an acceptable level.
Solarisation
This uses a plastic film to cover soil and trap enough heat to kill weeds, weed seeds and other soil-borne pests or pathogens. It relies on high levels of heat and solar radiation to be successful.
Plastic film must be thin and can be either clear film or black. It must be left in place for a number of weeks in the summer/hottest months. This technique has been shown to kill weeds, reduce soil-borne pathogens, seed germination and increase yields of productive crops (where used in productive horticultural or agricultural settings).
It is particularly useful in reducing annual weeds. A number of the studies found that approximately 30 days was very effective for the soil/weeds to be solarised¹.
Steam
This is generated from water heated to close to or beyond boiling point in some commercially -available saturated steam weeding devices. When applied to a plant/weed via a nozzle/head it causes the plant cells to rupture then wilt and die. It is more effective on very young or just emerging seedlings. As the plants get older and plant tissues thicken, its effectiveness is lowered. Germination of seeds may be stimulated in some species if they require higher temperatures. Unfortunately, this method requires a high energy input.
Hot Water
Application of hot water has effectiveness similar to glyphosate for annual weeds and young perennial weeds. But like steam it requires a high energy input (during manufacture) and repeated applications.
Direct Flame
A hand-held fossil fuel-powered burner (usually fuelled by propane, butane or LPG) can be used to control woody weeds in sensitive or riparian areas. Flaming is a technique where a hot flame is passed over the vegetation in order to increase the temperature of the moisture in the plant cells causing the liquid to rapidly expand and rupture the cells causing death. This can be used effectively on hard surfaces (paths, gravel, concrete etc.) but poses a fire risk if used in areas where combustible material such as mulch or dry vegetation is present.
Some research suggests that flamers should have a shield which keeps the combustible gases close to the ground for a more effective treatment. Many plants require frequent/repeated treatment to keep weeds at acceptable levels.
Biological Control
There are various biological controls for weedy plants. Introduction of specific pathogenic organisms or species is more the domain of government rather than home and community gardeners. A well-known example is the introduction of the Cactoblastus moth introduced to control prickly pear.
Goats
Control of weeds by goats is an approach that gardeners can use, but really only where the weed is more attractive to goats than other surrounding vegetation. It can help stop the weed from flowering, therefore reducing seed dispersal. It can also achieve ringbarking of woody species which will structurally weaken or kill the weed.
Some weeds are highly palatable to goats including scotch broom Cytisus scoparius, sweet briar Rosa rubiginosa, blackberry (Rubus fruticosus agg.) and wild turnip Brassica tournefortii. These species can be grazed all year round. There are many other species of weed that goats find palatable many of them weeds².
Integrated control of heavy infestations of blackberry, sweet briar and scotch broom can take several years and is best done using approximately 30 goats per hectare of fenced-in weed infestation. Goats should be stocked from early spring to allow them to defoliate, browse and ringbark the weeds and should be de-stocked over winter. This cycle should continue over two successive years. However, for this to be fully successful, spraying with strong weed killer in February is recommended followed by burning in April.
Chemical Control
Chemical control is the last resort in weed management. Herbicides work in different ways:
- Some herbicides kill plants by blocking enzyme activity that is required for plant cell activity.
- Non-selective herbicides kill /damage almost all plants
- Selective herbicides kill/damage some plants but not others - much of the time selectivity is achieved by applying the herbicide to specific plants.
Herbicides may be classed as:
- Contact - affects parts of plant directly contacted by the herbicide
- Translocated - applied to plant surfaces and then moved around the plants vascular system to damage the entire plant.
- Residual - the herbicide is applied to the soil and is absorbed by germinating seeds or plant roots. Such herbicides can remain in the soil for long periods of time.
All herbicides must be registered in Australia by the APVMA and are registered (permitted) for use on particular plants in particular situations. Directions for use are detailed on the instruction sheet and product packaging. It is essential that the instructions on any label are followed exactly. Even then, they pose risks to human health and that of other species - SGA’s WiseGardening app provides comprehensive information on potential side effects of herbicides available to the home or community gardener.
Any use of a herbicide which does not comply with directions is considered ‘Off-Label’ use and is then not covered by any warranty, so that the user becomes responsible for all environmental safeguards, occupational health and safety, animal welfare and any potential herbicide/chemical residues.
Bioherbicides
There is ongoing research on development of herbicides whose active ingredient is a living organism³.
There is, however, another type of product also termed "bioherbicide" which is very different. An example is Beloukha Garden Herbicide made from sunflowers to yield nonanoic acid where the active ingredient is a product derived from a living organism. However, the chemical nonanoic acid is used in some other herbicide products which are NOT bioherbicides, to increase effectiveness of low concentrations of glyphosate.
We are very grateful to Bridey Oliver for the research and first draft of this article and to financial support from the Lord Mayor's Charitable Foundation.
References
- Paiman, Yudono P, Sunarminto, BS, Indradewa D. 2020. Soil Solarisation for Control of Weed Propagules. Journal of Engineering Science and Technology Vol. 15 (1) 139 - 151.
- NSW Department of Primary Industries. Meat and Livestock Australia. 2007. Weed Control using Goats: A guide to using goats for weed control in pasture. Appendix.
- Kremer RJ. 2019. In Nano-Biopesticides Today and Future Perspectives,