Un-dumb Wicking beds

That’s a bit harsh. There is a fundamental difference to the following design though, that I haven’t seen documented on the whole of the internet, so here it is.

A wicking bed is a large scale self-watering pot. There is a reservoir of water you can access underneath, and as the soil drys out, the water is wicked up from the below,  prolonging the time between required watering and the inevitable death of your plants.

When there is a rain event, the bed harvests it’s own water which it will then make use of over a long period of time.

The soil is not going to dry out as long as there is some water in the reservoir.

The water is being delivered efficiently to the roots of the plant, where it is needed. It is being insulated by the soil… and er… mulch (pretend there is mulch on top of the soil in that diagram).

You aren’t as dependent on irrigation, which is less efficient, and easy to brake.

The fundamental difference

Traditionally, people have used a layer of gravel and drainage pipes to hold the soil above the water. The downside to this is that the gravel displaces the water. It’s a technique for building drainage into beds. Alternatively you can use something that takes up less space- that’s all. The water will last longer. You don’t need to get gravel, move gravel, etc.

Credit to Lachie from Tree Frog Permaculture for this pearl of wisdom (that man has whole a van full of pearls!).

No gravel technique

Bath tubs are good, long lasting, water proof vessels which are easy to come by. I can pick up light weight steel tubs for $20 (or less for several) at the local tip shop. They are often pre-plumbed for drainage too.

I build a frame out of recycled hardwood, which is also easy to come by at the moment the timber for this bed was picked up from a building site for free on the way to the job, advertised on Gumtree (Craig’s list, whatever). I won’t go into details about how I built the frame as carpentry is not my expertise. But simply: hold the tub up to a comfortable working height and give yourself room for the plumbing (or dig out a trench).

10cm pvc drain pipe is used to support the weld mesh. Pvc pipe is also easy to come by as a recycled building product and I haven’t had to buy any yet. It is strong and doesn’t displace much water. The weld mesh is cut and bent up to fit the contours of the tub and stop the soil from entering the water.

Geo-fabric is used to line the weld mesh. The edges are tucked under the weld mesh like a bed sheet, so that the fabric is touching the bottom of the bath – in contact with the water even when there is only a little. some extra pieces are draped over in the middle to help with even moistening of the fabric.

Fill the bed with water up to 2cm below the mesh and cut the riser pipe to the level of the water. This will stop the bed from becoming water logged. You will always  be able to gauge the level of water in the reservoir by looking down this pipe.

That’s it. Fill your bed with some good soil… keep enriching it with some nice home made compost (you are turning your food scraps into compost, right?)… and don’t forget to mulch it!

Here’s another design using the same principle. In this case, builders plastic forms the water proof seal and a plastic pallet is supporting the soil.