How to boost sustainability, enhance plant health, and increase productivity while slashing water consumption in your garden, writes horticulturist Aleisha Lynch.
When I wanted to create an abundant, healthy, and productive vegetable patch for my family at home on our farm with limited water to use, I decided wicking beds were the perfect, sustainable, and water-wise choice. Our home and garden are completely off grid for water supply, rainwater tanks are our only water source in a hot, summer dry, South Australian climate. So, when I learnt that the wicking bed system can reduce water usage by up to 80 percent, I knew this would be a successful investment.
What is a wicking bed?
The term ‘wicking’ means to absorb liquid or draw liquid up through a capillary action or motion.
A wicking bed is a raised garden bed, vertically divided in two parts: the lower part is a water-tight reservoir to hold water, and the upper part of the bed is the soil where the plants grow.
This system allows moisture to freely absorb from the reservoir into the soil at a consistent rate, maintaining the perfect moisture level for healthy plants. Evaporation is greatly reduced using this growing method, making your wicking bed very sustainable and water wise.
What grows best in wicking beds?
Everything! If you have constructed your wicking bed with the specific 300mm depth of soil and filled with a good quality organic soil compost blend, then your opportunities are endless.
Grow healthy herbs, leafy greens, root crops, brassicas, legumes, onions, and all the fruiting crops including tomatoes, zucchinis, cucumbers, pumpkins, capsicums and more.
How to build a wicking bed
Firstly, you will need a watertight base in the bottom part of the bed to hold a large volume of water. This could be achieved by upcycling a food-grade Intermediate Bulk Container (IBC). Alternatively, you can convert a raised garden bed by lining it with a heavy-duty pond liner to make the container water-tight.
The number one rule is that you need 300mm depth of soil at the top for successful wicking. Any deeper, and the water won't wick properly, leaving the soil too dry. If the depth is too shallow, the soil will get too soggy for good plant health.
1 Measure 300mm for the soil at the top; this will determine the height of the reservoir.
2 Add the overflow pipe at the exact height of the top of the reservoir.
3 Lay ag-pipe at the bottom, attached to a PVC pipe for your water inlet. The ag pipe will allow water to evenly flow through and fill the reservoir.
4 Fill the reservoir with rock up to the top of the overflow point.
5 Add a layer of geotextile fabric on top of the rocks to divide the two layers, then fill with 300mm of soil. The geotextile fabric will keep the soil from washing down and clogging up the water reservoir.
Maintenance is easy
Simply top up the water reservoir in the base of the wicking bed every 5-7 days and let the wicking system do the daily watering for you!
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