Wicking beds can be purchased, but many sold as ‘wicking boxes’ do not actually wick. Before buying, read our article on the countless ways to make wicking beds and make sure to watch out for many of the common misconceptions and design flaws of commercialised and popularised wicking beds. Proper wicking beds are easy to make. Any container or structure that can be made waterproof with a plastic liner can serve as a wicking bed or box.
To function correctly, a wicking bed requires:
- A 90 mm PVC pipe to hold about half of the plant-available water below the level of the overflow pipe and the bottom of the bed. The other half is held in the open spaces between the soil particles – water that would normally drain away.
As the pipe fills up quickly but the open spaces only slowly, filling up a bed with an open tap to get it fully filled means coming back once or twice after water comes out of the overflow; with the tap only partly open it takes a bit more time. - A fill pipe: from the surface into the reservoir pipe for refilling.
- An overflow pipe: An overflow pipe from the top of the reservoir pipe through the wall to the outside, to prevent beds and boxes from becoming a swamp during heavy rain or over-watering.
Common Wicking Containers
Styrofoam Boxes
Styrofoam wicking boxes can be placed on tables for easy access. They are portable, durable (lasting over ten years), and help regulate soil temperature. They are also easy to make and often available for free from greengrocers or vegetable wholesalers. (See making a Styrofoam wicking box)
Wicking Tubs
Larger pots and tubs can be converted into wicking containers by adding a plastic liner (if necessary), a 90 mm PVC reservoir pipe, a fill pipe, and an overflow. Black tubs may overheat, so surrounding them with shade cloth can help regulate temperature. Tubs can also be moved easily using a trolley.
Wicking Beds
Wicking beds are permanent structures that come in various shapes, sizes, and materials. (See the countless ways to make wicking beds for examples.)
Key Guidelines
- When building your wicking bed, it is important to keep the following essential requirements in mind.
- An overflow pipe should be fitted 100 mm from the bottom to prevent the box from swamping from excess water.
- Soil and mulch should not exceed 400 mm above the water reservoir.
- No plant should be more than 350 mm from an outlet hole in the reservoir pipe.
- A U-shaped reservoir is required for beds wider than 800 mm to ensure even water distribution.
