Wicking beds make for a water-smart garden.
IN the car space of his Clifton Hill flat, Frank Fisher now grows vegetables. Late last year, together with neighbours and enthusiasts, he fitted two old apple crates as ‘wicking’ beds – a water-efficient system in which the plants quench their thirst from below.
A long-time bike rider and sustainability professor at Swinburne University, Mr Fisher has no need for parking, but he spends much of the week out of town, so he wanted a garden that wouldn’t require constant attention.
Wicking beds can consume as little as half the water of a normal vegie patch. The technique mimics the natural system by which plants access moisture rising up from the water table.
“They’re optimally self-maintaining,” he says. “I’m growing a big selection of vegies, from leafy lettuce to carrots, tomatoes, broccoli and all sorts of herbs.”
Hannah Moloney, from Cultivating Community, says wicking beds can be used in large-scale cropping or backyard pottering. They’re ideal for container gardening in courtyards, balconies or rooftops.
To start, you need to line a container with strong black plastic (or use a water-tight vessel such as an old bathtub with a plug). Place an L-shaped length of piping along the bottom of the container, with holes on the underside and one end protruding for an inlet.
Cover the pipe with gravel, then lay shadecloth or geotextile on top, and add soil or compost (no more than 30 centimetres). Drill a drainage hole level with the shadecloth.
“Invest in the best organic soil you can get,” Ms Moloney advises. “It’s the difference between making or breaking growing in containers.”
Water your new vegie patch by pouring directly into the pipe. If you mulch the soil well, you’ll avoid evaporation altogether.
“The plants draw the water up by capillary action, through the gravel, through the geotextile or shadecloth, and into the roots where it’s most needed,” Ms Moloney says. “Wicking beds are the most water-efficient way you can grow vegetables.
“You can kill plants by not giving them enough water or by drowning them with love – that’s very common amongst urban growers. Wicking beds are really good because you know there’s enough water when it comes out the overflow. You can’t over-water, so it’s a fantastic technique for nervous or forgetful gardeners.”
The technique was pioneered by Queensland engineer Colin Austin during an aid project assisting African farmers to maintain food production under drought conditions.
“He found that the problem often wasn’t permanent drought, but that they had erratic rain – a monsoon or flood and then nothing for six months,” Ms Moloney says.
“He experimented lining small ditches with plastic so the crops’ roots could always access a reservoir. The beds are designed to consistently provide water to vegies, so they have a reliable food source.”
As climate change brings on more extreme weather patterns, the system may prove increasingly important to ensure food security.
For Mr Fisher, the garden has also become an easy way to spend time with neighbours. “We planted the boxes and had a beaut little celebration and BBQ. And there are various residents who are helping with the watering and maintenance,” he says.
“I’ve got the middle flat. Everybody goes past it. All I have to do is get out there and tend to the garden and the passers-by talk to me.”