Aug 142012

Progress Updated March 2013

When I built my first wicking worm bed 10 months ago, it was a test bed designed to gain experience with the process.  My plan was to eventually convert my vegetable and fruit growing backyard from conventional organic drip line gardening to wicking worm beds. 

As far as I am concerned the experiment was a success.  Soil fertility has improved and vegetables remained pest free without resorting to external inputs of fertilisers and pesticides.  Water use is significantly reduced, yet soil condition has been maintained at optimum moisture levels. 

I have just built my first large wicking worm bed designed to replace one of my 4 conventional beds, but last spring I built 3 new beds of a different design.  I wanted to explore a cheaper more versatile option for potential gardeners who have little or no access to a garden of their own.
Two years ago I began my retirement with a desire to create a model backyard vegie garden. I wanted it to carry the lightest carbon footprint possible, and conserve precious water supplies. I had started out years earlier by the conventional organic route, with no synthetic chemical fertilizers or pest controls. I had installed water tanks and surface drip irrigation, and I had composted large amounts of material in my twin bin arrangement.

I was happy with the results, but during the recent years of drought, I had found it hard, even to average over a year, Melbourne’s drinking water target usage of 155 litres per person per day. So I began my search for a better way, and about a year ago, I came across Colin Austin’s wicking bed innovation. (see

I began to experiment with cheap 60 litre bins (see above) with great results. The vegies always had enough water, yet used very little. Recently, I built a larger unit with a built-in worm farm, and pest exclusion frame. (see above behind wicking bins).

My aim with this unit is to restrict consumption of fertilisers, pesticides and water to a minimum. (even organic fertilisers and pesticides). The theory is that by incorporating a worm farm into the wicking bed, the whole bed becomes part of the worm habitat, and the soil is fertilised and aerated by worm activity. Microbial activity is enhanced by the breakdown of Pine bark in the water reservoir. Fertility in the reservoir is also boosted by the direct leaching of worm wee from above.

I am uncertain at this stage what will happen to all the worm poo. At this stage (2 months worm activity), I seem to keep adding new waste to the farm all the time and I assume it is being distributed as poo throughout the bed. If it builds up too much in the worm farm, I may need to empty one side periodically and apply the worm poo (and accompanying worms) as a top dressing in the open bed. The worms will find their way home.

If all goes well, the only additions to the system, apart from water, will be vegetable waste from garden and kitchen.

Wicking Worm Bed 1500mm x 900mm x 600mm

The bed is partly buried in the ground, and the timber walls of the bed are lined with pond liner to enable a water reservoir to be created in the bottom 300mm of the bed. Below the shade mesh shown in the photo above is a 300mm layer of aged Pine Bark Chips. The shade mesh acts as a barrier stopping the soil from mixing with the Pine bark but allowing water to wick up out of the reservoir into the soil.

Right at the bottom of the reservoir is a double loop (shaped like an 8) of 50mm slotted irrigation pipe joined by a moulded PVC “T”. A vertical piece of 50mm PVC tube is attached to the “T” and extends above the timber walls (as shown above). This arrangement allows the reservoir to be filled from the top without soaking the soil and plants.

Just inboard of the filler pipe is a fibro cement divider set so that there is a 70mm gap between it and the shade mesh barrier. This divider separates the soil in the open bed from the decomposing waste in the worm farm. The above photo shows the bed partially filled with good soil to a height of 70mm above the shade cloth barrier. This layer of soil extends under the fibro cement divider and into the worm farm allowing the worms access to the open garden bed. The open bed is then filled to the top with more soil.

A 3 piece cover protects the worms from sunlight and predators, and provides access to the worm farm. A strip of shade mesh is used to provide further protection for the worms and help contain moisture. The filler tube is capped to prevent access to snails, slugs and mosquitos, and a water level gauge pokes through a hole in the cap. This gauge is simply a table tennis ball glues to a light stick. The stick is painted with the high and low water level marks.

Just visible in the bottom middle of the photo, is a 13mm drain hose, which is set just under the shade cloth barrier level. This drain allows you to accurately fill to that level, and prevents overfilling in the event of heavy rain.

The metal angle corners serve to hold the timber walls together, and support a set of removable frames covered with insect exclusion netting. The netting is rated at 21% shading, and this will provide summer protection against Melbourne’s fierce summer sun. It remains to be seen how successful this prototype backyard wicking worm bed is going to be, but if it works well, I intend to replace my conventional beds with larger versions of it.

John Ashworth

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  12 Responses to “Sustainable Wicking Worm Bed”

  1. Thanks for the info. I find a double layer of shade cloth is even better at keeping the soil in place.
    Jeanette W.

  2. Thanks Guys,

    I must say, I didn’t expect you to comment through the SGA website, but vey nicely done anyhow. Look forward to seeing you soon.

    From Grandad

  3. hi grandad,
    the information was really interesting to learn and the garden looks great! its very inspiring how much time and effort you have put in to all of this. The wicking beds are a functional way to grow veggies in a small area and is a smart way to grow your veggies. hope all goes well for you and the blog looks great!

    from Jordan and Toby 🙂

  4. Hi Graham

    I am very interested in what your doing with your wicking bed water supply. Do I understand you correctly that you manually or mechanically flood the bed to a (variable) level, then drain the water out of the bed? then repeat the cycle periodically as you would with a hydraponic system.

    On the subject of worms, I get good results by alternately feeding the two sides of the worm area. I feed them once a week with about 4 cups of finely chopped food and a layer of shredded newspaper on top.

    My next wicking bed (which will be larger than my prototype) will have a worm farm at each end. I will add feed to one end for maybe a month before switching to the other end for the same period. I want to encourage the worms to constantly migrate through the planted area looking for food. With luck this will encourage mobility thereby increasing aeration and fertiliser distribution.


  5. Thanks for the article John.
    I have been using old fridges to create wicking beds and thought you might be interested in one variation on your design. My outlet is from the very bottom of the bed and leads to a flexible pipe which can be lowered or raised to vary the height of the water inside the bed. This allows for the different preferences of different plants and it also allows a system of “flood and drain” used in aquaponics.

    I like the way you have partitioned off the worm area. I have been using ice cream containers with the bottoms cut out but your way would provide for a lot more food to be added.


  6. Hi Kerri

    Thanks for your kind words. Your right about the overflow tubes, but I tend to use the levelling devices to guide me when filling the tanks. The only time I get overflow is when it rains, and unless I already have full tanks, the rain is absorbed. Despite this, I will take your suggestion on board for future beds I might build. Every bit of water counts. Incidentally, apart for initial testing, I have not seen the large experimental bed overflo, nor have I had to fill it (in about 3 months). It will be interesting to see what happens in the heat of summer, and with mature crops.



  7. I should have signed off Ken

  8. Thanks John, Iam keen to try will let you know and trade some pics, where are you from?

    • Hi Ken

      I am pleased you are having a go, I plan to build a 600mm cube wicking worm bed for a dwarf lemon tree (Meyer) when I get time. I always have trouble getting the soil just right for fruit trees in tubs. I am hoping the new wicking worm tub will resolve this issue and eliminate the need to regularly repot the tree. I live in Melbourne where it is hot and windy and very dry in summer.



  9. Wow, your worms have the best house in the street! Very nice.

    I notice all your overflow tubes head out to the paved areas. Is there a reason you didn’t face these in to the existing gardens so they get watered, too?

  10. Hi Ken.

    I dont have a schematic, but I will describe it to you:-

    The bottom half of the bin contains scoria (or other medium to support the soil and create a water reservoir). A circular piece of shade cloth is placed on the scoria to prevent soil falling into the reservoir.
    Before the scoria is placed in the bin, however, a filler tube and distribution pipe needs to be installed. I use a 50mm rigid pvc filler pipe attached to a 50mm slotted irrigation pipe (formed into a circle) using a 50mm “T” piece.
    The circle of slotted irrigation pipe should fit tightly in the bottom of the bin, and the PVC “T”section set at 90 degs so that the filler pipe fits vertically upwards to terminate about 75mm above the rim of the bin. Make a hole in the shade cloth for the filler pipe.
    Just under the level of the shadecloth, a 13mm plastic drainage pipe is installed through the wall of the bin, and then the bin filled with good quality soil with plenty of compost and organic fertilizer.
    I use a 50mm cap on the top of the filler pipe to exclude pests (snails and mossies) and through a hole in the cap I use a water level indicator, which is a table tennis ball superglued to a light 5 mm dowel. I mark the stick with high and low water levels. The ball fits neatly inside the 50mm pipe.
    Its fairly important, I find, to allow the water to fall to the low level before refilling. The plant roots need air as well as water. You can see at a glance when the reservoir needs filling.
    I also use a piece of stick-on copper strip around the top of the bin to keep the dreaded snails and slugs at bay.
    I recycle my soil every year with new soil from the vegie garden and compost from my bins.

    Good luck


  11. Hello, do you have a schematic of the 60 litre rubbish bin set up please I am really interested in this approach particuarly now we have just had a water metre installed.

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