Post on 14-Aug-2015
Wicking Beds by Travis Mitchell
If you garden in raised beds you've probably spent a lot of time watering and this year probably even more than usual. Raised beds offer the gardener a myriad of advantages but being water wise is not among them. So what is the water conscious square foot garden devotee to do? One solution is wicking beds. Wicking beds take advantage of soil's ability to wick water up through capillary action; the same process that occurs when you stick the end of a Kleenex or paper towel in water. In a wicking bed there is a water reservoir underneath in contact with your soil or potting mix, which allows watering of the garden from below. A popular example of a wicking bed system is the Earth Box, but there are many DIY examples and no reason to limit yourself only to containers. At the Downtown Farmers Garden we are in the middle of replacing a traditional raised bed with a wicking system. The specifications for constructing a wicking bed vary, but a universal principle is that water can only wick effectively up to one foot. The design we settled on starts with a one-‐foot deep hole, four by eight feet wide, in which our two-‐foot tall frame will rest. Next, a layer of weed barrier or ground cloth (we may add sheet metal, thicker cloth or plywood below this to block roots from a neighboring oak tree) is laid on the ground and up the edges to smooth out the surface for the liner. Pond liners were a bit pricey so we decided on 6 mil construction plastic sheeting which we will double layer in case of punctures. A six-‐inch layer of gravel, or stones along with the watering pipe is laid down which will comprise the water reservoir. Another layer of ground cloth is laid atop to prevent soil from entering the reservoir and the six inches of soil, which will act as the wicking layer. Above the wicking layer drainage holes are placed to allow escape of excess water. In Florid, heavy rainfall is commonplace, so we will be drilling ample drainage holes to prevent flooding. The next layer is shade cloth or another very porous fabric to allow wicking but discourage roots from entering where they are likely to get drowned. Finally, the remainder of the bed is filled with soil, in our case a mixture of the GM2 mix from Soil Enrichment Products, and some native soil we displaced digging our hole. These systems are growing in popularity, especially in arid regions, but are still new and long terms effects to the soil and their durability are not well documented. To see a more detailed account of the wicking bed at the Downtown Farmers Garden and follow our other gardening adventures go to downtownfarmersgarden.blogspot.com or friend us on Facebook. http://www.sgaonline.org.au/?page_id=5533 http://permaculture.org.au/2011/06/20/from-‐the-‐bottom-‐up-‐a-‐diy-‐guide-‐to-‐wicking-‐beds/ http://www.theruralindependent.com/garden-‐projects/wicking-‐beds