Keyhole Gardens. Productive Small Footprint Gardens
By Kathleen Reynolds
You want to grow vegetables and fruit to feed yourself, but you only have a tiny garden area. What if you wanted to feed your family, your extended family, what about your village? Oh, and there’s a drought.
A keyhole garden may be the answer. The garden takes its name from a small, usually circular, garden with a small path, or notch, that dead ends in the middle, resembling an old-fashioned door keyhole. The garden can also be square, V-shaped or in a mound and the walls can be fashioned from any material that can hold soil: sticks, logs, rocks or bricks.
The concept was developed and adopted by humanitarian organizations in the 1990s in the sub-Saharan regions of Africa to help combat hunger by teaching people how to grow their own food. It’s been estimated that over 20,000 keyhole gardens have been built there.
Most keyhole gardens are roughly six feet in diameter with walls about waist high, eliminating the need to kneel or bend over to tend to the plants. Some have stakes or rough arbors over the garden so a shade structure can be added in extreme heat or even to protect against frost conditions.
In simplest form, at the end of the path is a wire cage, basket or vessel with drain holes, into which kitchen waste and cardboard is composted. Keyhole gardens hold moisture and nutrients because of the compost pile. The notch makes it easy for the gardener to add kitchen scraps to the compost as well as ease of planting and harvesting. The garden has a drainage layer, a soil layer, and a planting area, everything that plants need to thrive. When it rains or when you water the compost, the nutrients seep into the surrounding planting bed.
“Keyhole gardens are good because you devote less space to the pathway and more to the garden,” says Rachel Kohn Obut, owner operator of Little Moon Farm and a teacher of ecological gardening and other topics for Napa Valley College’s Community Education. “You can have one little garden or a network of keyhole gardens depending on your space.”
“A keyhole garden is one aspect of permaculture, a philosophy of gardening in a way that most imitates nature,” says Rachel. “It is built on the principals of sustainability, minimizing pathways and interplanting different plants.”
“Plants in keyhole gardens look more natural, not in straight lines, because they grow the way nature grows. It’s more beautiful,.with curves and patterns.”
Penny Pawl has been a Napa County Master Gardener since 1997 and has mentioned her keyhole gardens several times when she writes for the “Napa Register Master Gardener” column.
“I have four keyhole gardens and use worms in them,” says Penny, who explains that the worms decompose the composting material, and their castings enhance the soil around them. “I grow bonsai and first started using worms because their waste product is good for bonsai moss. I’ve got eight worm beds, including one in each keyhole garden. I use garbage cans as the compost bins, some without bottoms and some with bottoms and holes drilled into them for drainage. The idea is the worms travel back and forth between the compost and the soil.”
The compost bin for the keyhole garden uses the same materials as a worm bed: cardboard, kitchen waste, dead plants and newsprint.
“They love cardboard and go through it much faster than newsprint,” she says. “They like the taste of the glue used in cardboard. The glue contains formaldehyde that’s tasty to them. Sow and other bugs also thrive in worm beds. I leave them there because they help fertilize the plants, too. One of my gardens has a lizard living in it; another has a frog. I like them because they keep the fruit flies down.”
Penny puts cardboard on top of the compost scraps and covers the top with plastic. “You have to keep all the elements moist for the worms to thrive,” she explains and chuckles. “I have to replace the worms occasionally because they run away from home.”
Another strong proponent and instructor of keyhole garden construction is Deb Tolman, PhD, from Clifton, Texas. An environmental scientist and landscape designer, she co-founded a non-profit focused on sustainability, the Silo Project, and authored the book, “Soiled Rotten: Keyhole Gardens All Year Round.”
“There is no compost that goes into the keyhole garden using my method; no native soil,” writes Deb in an email. “It’s complete science which makes the shape not mine, but the method is definitely inspired by me. We make compost in less than four weeks with nothing but cardboard, tons of it, and manure.”
Her website (debtolman.com) provides instructions on how to construct a keyhole garden. There are other permaculture variations of the keyhole concept.
One of them is “hügelkultur,” a centuries-old, traditional way of building a raised garden from rotten logs and plant debris. These mounds can be 5 to 6 feet high, made of logs, branches, leaves, straw, cardboard, grass clippings, and manure. Over time as the wood breaks down, a “hügelbed” sinks, up to a couple of feet, after the wood decomposes and settles. Because of the base of compostable material, keyhole gardens have been shown to be among the most productive small footprint gardens.
For those wanting additional information on keyhole gardens, Rachel Kohn Obut recommends the book Gaia’s Garden: A Guide to Home-Scale Permaculture” by Toby Hemenway.