What is a Wicking Bed?
Wicking beds are garden beds. They use a method of gardening where the garden bed has its own reservoir of water under the soil. This is achieved by placing a waterproof barrier in the frame of the bed. Then filling it with material that promotes the soils natural tendency to wick moisture up.
You see this in nature, along river banks and waterways. Up to a foot above the water level is wet. We are taking that physical property of soil, and using it in our gardens. Generally, the bottom layer is a course gravel material, followed by a root barrier. From there, the bed is filled with planting soil designed for planters. Check out Wicking in Action for more on this.
Generally, wicking beds are raised beds, but not always. I have built a Dogwood hedge using this method.
They are also referred to as self-watering beds. This is misleading. They are self regulating. They will only fill so much before draining. However, they do still require water input. The result of the water being stored under the soil, is less water wastage due to evaporation. As well, the plant roots are being drawn deeper into the soil. This action will make them stronger and more drought tolerant.