Americans whose gardens have been toasted by prolonged drought might consider a landscaping concept from Africa. It’s called keyhole gardening, and some believe it’s the ultimate in raised-bed design — a sustainable combination of composting and planting.
Keyhole gardens are small — typically no more than 3 feet high and 6 feet in diameter — and when viewed from above look like keyhole assemblies in doors. From the side, they can resemble a tall earthen pie with a giant slice taken out.
They don’t need fertilizer, use 80 percent less water than the normal backyard patch, tolerate hot climates and are easier to tend because they’re at waist level. No bending or kneeling required.
Keyhole gardening was pioneered in Africa and became popular there again recently through initiatives by humanitarian aid groups.
A keyhole garden’s primary asset is drought tolerance, although it also works in temperate climates, said Eddie DeJong, co-founder and head of business development and design for Vita Gardens in Sarnia, Ontario. The company makes keyhole garden kits.
The gardens get their nourishment from compost and water poured down an open-ended tube in the middle of the garden bed.
“The central composting basket is the key to making this an effective gardening solution,” he said.
“After the garden has been established, it should be watered primarily through the compost basket and less and less around the bed itself,” DeJong said. “This trains the vegetables to grow deep roots down to where the moisture and the nutrients are.
“Furthermore, if the garden is layered as intended, local yard waste like grass clippings, palm fronds and other materials are converted into rich soil, making the entire bed a composting nutrient factory.”
Keyhole gardens are cheap and simple to assemble. African children often build them in schoolyards or for their families.
Structural components include native and recycled materials as straw bales or bricks. “We don’t use waste lumber because it rots down too easily,” said Rose Marie Nichols McGee, president and owner of Nichols Garden Nursery in Albany, Ore.
Some commercial kits offer a more tailored look for use on patios and decks.
DeJong said his company is working on lighter, more compact sizes for keyhole gardens, and “aluminum and composites for a modern urban look.”
Keyhole gardens have proved to be more productive for McGee than regular raised beds.