Wicking beds: Irrigation from the ground up

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Seven years ago, when permaculture design consultancy Very Edible Gardens began, they had no idea what a wicking bed was. After repeated queries from clients, they started to research and experiment. Dan Palmer, co-founder of VEG, shares the fruits of their labour.

Prior to our foray into wicking beds, all of our raised vegie beds were either unirrigated or set up with drip irrigation. But then someone whispered these words to us: “Wicking beds… We want wicking beds.” So we started setting up wicking beds in old bathtubs, and using plastic liner in standard raised beds. We set out to learn by doing, our initial intention to prove to ourselves that wicking beds didn’t work. We gave it a pretty good shot, learned a lot in the process and refined how we went about them—a good example of iterative design, where you keep doing what’s working and improve what isn’t, then repeat.

What is a wicking bed?

Invented by Australian Colin Austin, the wicking bed idea involves the prevention of water loss from your garden bed through the use of a waterproof liner or layer. This creates a reservoir of water beneath the soil and means that, instead of watering from above via drip irrigation, a hose or a watering can, the water wicks up into the soil from below.

This keeps the soil nice and moist. You prevent the weight of the soil from squashing all the water out by having the water sit in a layer of small stones, sand or similar, which can accommodate the water while bearing the weight of the soil. You prevent the soil from dropping down into gaps between the stones or sand particles with a layer of something that lets water wick up, but stops soil moving down. The last essential piece of the wicking bed puzzle is that you need a designated overflow point so that the soil layer doesn’t get flooded and kill the soil life and plants by rotting their roots.

Read the full article in ReNew 135.

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