What is a wicking garden bed?
The term wicking refers to the action of a liquid being drawn up into a medium by capilliary action.
This action is very useful to the gardener, in that a reservoir of water can be stored below a plant and used to slowly and consistently maintain moisture levels in the soil from beneath.
Remember those self watering plant pots that were popular a few years ago? Well they were using this very process.
The wicking vegetable garden bed became popular over the last decade as a solution to coping with the drought conditions prevalent across the country.
Although the drought has broken, they still have a number of benefits to the gardener, especially if you lead a busy life.
The following highlights just one design of wicking bed (shown above), a self contained, rustic garden bed that can be supplied and installed by Garden Box beds.
A wicking bed can be made from any container than can, or can be made to hold water so there are many options available, it all depends on how handy you are at DIY.
Of course, if you aren't 'handy' the beds below offer a great solution, complete and ready to plant.
Essentially a wicking bed comprises of the following:
The lower section, a water reservoir with filler pipe and overflow.
The soil barrier, a water permeable membrane that keeps the soil from clogging the filler and distribution pipe, but allows the water to pass into the soil.
The soil section
A compost layer
A mulch layer
A built in 'worm farm'
The wicking bed doesn't have to be a raised garden bed, they can be made into the soil, in you garden. As we have discussed the benefits or raised garden beds elsewhere on the site, we will stick with using a raised bed as the example on this page.
As we feature the Apple Crate bed below, we'll look at this design to explain the process.
Here we have a raised garden bed made from recycled timber apple crates, but you could just as easily do the same using one of the colorbond raised beds featured here.
The garden bed is lined with a water proof barrier, this can be either heavy duty plastic or a pond liner.
Obviously the interior of the raised bed must be carefully checked for any sharp edges, protusions etc as any of these would puncture the liner and allow the water to leak out.
At a point approximately 300mm below the surface level, a water overflow pipe must be installed.
Here you can see the overflow in the apple crate. This is essential to stop your bed from becoming waterlogged when it rains. If this was not included, the water level in the soil would continue to rise and eventually drown the roots of the plants, killing the crop.
The lower section of the bed, the water reservoir, is filled with water from the surface as needed. Water is added to the filler pipe and dispersed into the bottom of the raised bed via a distribution pipe.
It is essential that the distribution pipe is covered with a membrane of some sort that will exclude soil from entering the pipe.
'Ag pipe' is commonly used as this is perforated to allow water drainage out of the pipe into soil through slots that are incorporated when it is manufactured. Ag pipe can be purchased bare, or in a 'sock' of geotextile fabric.
Once the water area is set up and covered, the next layer is a 'membrane' of some sort to keep the soil separate from the bottom.
Shade cloth is quite common and provides a long lasting barrier.
The bed is then filled with your choice of soil/compost/potting mix. In one corner the worm farm is added.
The worm farm is a considerable part of the success of these gardens. Apart from providing a good way to dispose of some of your kitchen waste (vegetable scraps etc), as the worms consume the waste, they create nutrient rich 'castings' which feed your plants.
The worms are free to come and go from the garden bed soil and worm farm, improving the health of the soil as they do.
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