Wicking beds are a clever solution for areas with erratic rainfall or for people with little time for pottering in the gardening. They can be on areas with no soil including balconies, courtyards and roof top gardens (just be sure to check your building or balcony can handle the weight).
In a nutshell wicking beds are a fully contained garden bed with a false floor at the bottom which functions as a water aquifer.
On top of this is a layer of geo-fabric material to prevent soil from clogging up the water and on top of this is a growing medium, like soil, for plants to thrive in.
Using capillary action, aka wicking, the plant's roots draw water up from this aquifer - meaning you don't need to water from the top.
There are nifty design features including an overflow pipe to prevent flooding or drowning of plants and an inlet pipe where you can plug your hose in to top up the aquifer as needed.
Due to the vigorous Australian wildlife (possums and wallabies particularly) this design includes a cage on top of the bed. The key to a good cage is that is should be easy for anyone to use - this one's a beauty with strong hinges and timber props to keep it open while you harvest.
Before filling in the bed, the timber is lined with a food grade black plastic to keep all the water in.
Then we added blue metal gravel that had been flushed with water to wash off the fine dust that was on it. If we had our time again, we would've made sure that the gravel was slightly bigger and clean. But after washing, it was fine.
On top of the blue metal goes a geo-fabric material, its job is to keep the soil from clogging the aquifer.
A really clever design feature is the overflow pipe. It's built with an movable elbow join so if you need to, you can empty the water aquifer by turning it down.
What's a no-dig garden?
Developed by Esther Dean in the 1970s, no-dig gardening is a technique where you layer carbon and nitrogen materials on top of the ground like a lasagne to create a raised garden bed. You can go as high as you like - but generally people don't go over 1 metre. This creates a nutrient-rich approach to growing food crops and a brilliant way to build healthy soil when there isn't any onsite.
When we build raised gardens we always build them with the no-dig gardening method. This is because we're yet to find a commercially available soil mix we're satisfied with. We need our soils to be pumping with the biology, which a no-dig garden method provides.
The carbon material we had available to us on the day was aged hay from the paddocks - ideally straw would have been better as it's "seed free" but we use what we have. For the nitrogen layer we used aged chook poo. Each layer was watered in thoroughly to ensure there was even moisture throughout the whole pile.
Once the bed was full we planted it out with herbs for the kitchen. For each seedling we dug a small hole in the top and backfilled it with mature compost and planted directly into this.
We call these "compost pockets". This is a resource-efficient way of using what can be expensive compost. Instead of buying heaps of it, we only source enough for planting each plant. By the time the seedling's roots break through out of this pocket into the surrounding hay and chook poo below it will already be transforming into gorgeous soil.
There you have it, the wildlife-proof, no-dig-garden, wicking bed - productive, low maintenance and destined to provide many herbs and much happiness to all.
- Hannah Moloney and husband Anton Vikstrom are the founders of Good Life Permaculture.