Crop rotation – despite what my non-gardening mates believe, is NOT the twisting of sunflowers to chase the sun (although, they do have a point… they are crops, and they are rotating!). Crop rotation is in fact a method of managing plantings, both on a small (vegie patch) and large (farm) scale to minimise the risk of pests and diseases, and maximise the yield and productivity of crops. Yup, it all sounds terribly technical, but I promise you it’s not! Hey, if I can manage it, I reckon just about anyone can!

What’s the Deal?

The definition of crop rotation I like the most is ‘The successive planting of different crops on the same land to maximise soil fertility and help control pests and diseases.’ Okay, it sounds very agricultural, but, in essence, this is the principle that we, as home gardeners, can apply to our vegie patches. And let me tell you, it works. The top notch vegies that we grow in our yummy yards, almost always, remove many and various nutrients from the soil during their growing periods. That said, a number of them replace nutrients as well (think beans, peas and other legumes). By varying what we pop in the patch, and what type of crop follows another, we can ensure that our vegies get what they need from the soil… and we get what we need from our vegies!

The other benefit of rotating our crops is that the process helps to interrupt the cycle of host specific pests and diseases. This means that harmful pests and diseases are unable to build up to damaging levels either in the soil or on the host plants themselves. Crop rotation has ‘moved’ their favourite host plants from the area, perhaps whilst the pests were ‘resting’ over winter, and essentially they are now unable to breed or, if they do breed, they no longer have a food source for their young to thrive. Hence the cycle is broken! Hurrah!! Crop rotation is a common practice in many large scale agricultural endeavours, such as in the rice paddies in Southern China. Over a two year cycle, a rice crop is generally followed by an “upland”, non-related crop (such as sugar cane) to help break the cycle and infestation of rice borer. And it must work, cause these guys have been doing it for a long, long time! In fact, crop rotation is reportedly one of the oldest cultural practices that is still kicking around….early civilisations in Africa and Asia used it, as did the Romans.

So how do you do it?

Everyone and their gardening book has a different method for successful crop rotation. After much discussion in the SGA trenches, we have come up with a system we like a lot. It’s simple, easy to manage, and it works!

Our system works on a four bed rotation, meaning there are four separate planting areas. Don’t fret if your garden doesn’t seem big enough to cope with all these beds. You can instead have just one bed and rotate the produce each season. It may mean you can’t grow tomatoes every summer, but you’ll have fun with a lot of other vegies in between! Vegies you can trade for tomatoes at your local vegie swap. If your garden is large enough, use what space you have available, and divide this up into four separate “zones”. Or, if you are starting from scratch, consider a mandala circle style vegie garden. While they look amazing, they will also maximise space, and allow for the zoning of planting areas (which in turn makes crop rotation even easier!). You can even have a spot for the chooks!

The Four-Bed Crop Rotation System

Lets get down to the nuts and bolts of the whole thing… how to do it. Firstly, we need to know a little bit about plant families, because this is a key principle behind crop rotation. Essentially, each area should be planted with a different plant family each season (generally every six months), to help avoid any nasty pest and disease outbreaks. So, who’s related to whom?

Beetroot family
Swiss Chard

Marrow family

Potato family
Peppers (Capsicum and chillis)

Compositae (Asteraceae)
Daisy family
Jerusalem Artichoke

Umbelliferae (Apiaceae)
Carrot family

Cruciferae (Brassicaceae)
Cabbage family
Brussels Sprouts
Oriental Brassicas – e.g. Bok Choy

Leguminosae (Fabaceae)
Pea & Bean family

Onion family

Grass family
Sweet corn

The principle is that one family member shouldn’t be followed by another family member in consecutive seasons. For example, once the tomatoes, members of the Solanaceae family, have finished fruiting and been removed, this area should be planted up with a member of another family such as a peas from the Fabaceae family.

There is another reason for this type of planting sequence as well. We know that some plants are referred to as “heavy” feeders, while others are “light” feeders. By introducing a crop rotation system, we can estimate the potential levels of soil nutrients remaining in the plot and plant up accordingly. For example, the Brassiaceae family are mainly heavy feeders and will take a lot of nutrients from your soil. However the Alliaceae family are light feeders and will not do well in a rich soil. Therefore it makes sense to plants onions after cabbages! Sounds complicated? I promise, it’s not! Just think logically and you can’t go wrong!

With these principles in mind, a suitable four-bed crop rotation may look like this:

Season One Season Two Season Three Season Four
Bed One Legume Heavy Feeder Light Feeder Green Manure
Bed Two Heavy Feeder Light Feeder Green Manure Legume
Bed Three Light Feeder Green Manure Legume Heavy Feeder
Bed Four Green Manure Legume Heavy Feeder Light Feeder

Heavy Feeders include potatoes, tomatoes, cauliflower, broccoli, cabbage, sweet corn, lettuce, cucumbers, zucchini, spinach, lettuce and Asian greens.

Light Feeders include onions, leeks, garlic, beetroot, carrots, parsnips and silverbeet.

Legumes include peas, snow peas, broad beans, runner beans, snake beans which fix nitrogen.

Green Manure Crops are crops grown, not to be harvested, but to be worked back into the soil. These are generally comprised of thickly sown annual grasses and/or legumes, that are tilled back into the soil before they flower or form seed heads. They add nutrients during their growing period and organic matter to soil in veggie patches, perfect for getting the next seasons edible crop off to a good start! Many nurseries stock pre-packaged green manure seeds.

Keeping Track of the Patch

Like a lot of things, crop rotation works really well in theory, but can prove a little daunting, especially if you’re memory is anything like mine. The solution – a blackboard in the garden shed, or a gardening calendar, outlining what was planted in what patch during each season. This is a great visual reminder of what’s happened in your yummy yard, and will help you keep track of the rotations happening in your patch.

There really are no hard and fast rules when it comes to crop rotation, but, if you follow the four bed rotation above, and keep the following four tips in mind, I reckon you’re on the right track:

1. Don’t follow one crop with another from the same family
2. Don’t follow one heavy feeder with another heavy feeder
3. Do plant a green manure crop at least once in every 4 seasons to replenish your soil.
4. Do read the SGA fact sheets on individual plants when planning your next crops

Crop rotation may take a little bit of practice and patience to get right in your neck of the woods, but, once you’ve mastered it, it is as easy as 1,2,3,4!