For details of some local people who build wicking beds or raised garden beds, see the local resources page.
The purpose of a wicking bed is to substantially reduce the number of times that the bed needs watering. They are particularly suitable for community planter boxes which are often not close to taps and are therefore not easily irrigated.
Wicking beds have a waterproof lining that holds a large reservoir of water at the bottom. The water is drawn upwards like a wick via osmosis and thus becomes available to the plants. Basically it works like a self-watering pot.
See Yummy Garden’s page for a local take on the advantages and disadvantages of wicking beds.
Some instructions on how to build a wicking bed can be found on:
- The Urban Food Garden website. The big graphic above was obtained from the same website.
- The SGA website.
- Angelo Eliades.
See the resources page for a list of local people who make wicking beds professionally and whose services you might therefore be interested in.
In March 2017, Pam Jenkins, member of Local Food Connect, gave a presentation on wicking beds. Here are her notes.
What is a wicking bed?
- Bed with a reservoir below and a wicking mechanism to enable water to permeate up.
- Reservoir medium: scoria, polystyrene, open structure.
- Supports soil above.
- A barrier to prevent soil from clogging up the gaps- geotex.
- A waterproof membrane to contain everything.
- A drain at the level of the top of the reservoir.
- Inlet pipe with slotted drain attached to fill the reservoir.
Why use a wicking bed?
- Poor or insufficient soil to support plants.
- Dry climate.
- Competition from other vegetation.
- Usually a raised bed so less bending.
- Less frequent watering – none lost to surrounding plants or just leaching away.
- Water from below – less evaporation.
- Less spread of fungal disease caused by overhead watering.
- Able to heavily crop a smaller space.
- Focus on defined areas.
- Essentially they are large pots.
- No water from surrounding soil.
- Possibility of disease in reservoir.
- Possibility of over fertilising.
- If inlet not covered, can be a breeding ground for mosquitos.
- Completely dependent upon your inputs.
- Very heavy.
Types of construction
- Purpose built or re-purposed.
- Large pots and barrels.
- Old wash troughs.
- Old baths.
- Solid outer carcass.
- Level ground.
- Waterproof liner.
- Protective material over waterproof membrane.
- Wicking medium.
- Install pipe with lid for filling reservoir.
- Water permeable membrane – shade cloth or geotex.
- Drain hole level- use proper fittings and silicon in.
- High quality soil, compost, large amount of organic matter.
- 30 centimetres.
- Suitable plants – depth of soil.
- Care of seeds and seedlings.
- Water from top until roots long enough to capture water from below.
- Watering: check the reservoir. When the water looks low, top it up.
- If it has been allowed to dry right out you may need to water from the surface as well. Hot winds.
- Feeding: use half strength liquid fertilisers and half recommended amount of slow release pelletized fertilisers.
- Keep adding compost and well composted manure with each successive planting to maintain sufficient organic material to ensure that the wicking system works.
What could possibly go wrong
- Soil cover not thick enough – over-watering.
- Drain hole blocked.
- Re-purposed planter box gives way.
- Over fertilising / under fertilising.
- Not enough fibre in soil to promote wicking.
- Usual garden problems: snails, possums.