Planting a victory garden may have been last spring’s big trend, but if you’re looking to take your gardening to the next level, try the newest craze: a keyhole garden.
What is a keyhole garden? It’s a circular raised garden bed standing 2 to 3 feet tall, with a keyhole-shaped cutout on one side (hence the name). This allows gardeners to enter and easily reach all plants for easy access weeding, harvesting, composting, fertilizing, and more.
In addition to making gardening easier, keyhole gardens tend to yield more produce, based on their innovative design. Here’s more about keyhole gardens, how they work, and what it takes to build one in your own yard.
What is a keyhole garden?
Keyhole gardens originated in Lesotho, a small country in South Africa. Due to the arid climate here, these gardens are built to flourish amid dry conditions and in areas with poor soil quality.
The key to a keyhole garden is its center—a raised mini compost container where gardeners add food waste and manure, which decompose and then seep into the surrounding soil.
“When you add compost in the center, it decomposes and feeds the plants around it,” says Hector Mardueño, owner of Las Vegas landscaping company Stonewall Creek.
Since these nutrients spread only so far, this is why keyhole gardens are round, and not too large.
How does a keyhole garden work?
Another smart aspect of keyhole gardens is the layers of compost within these raised garden beds, says Chelsea Wells-Barrett, gardening expert and founder of the blog Grow Where You Sow Homesteading.
The bottom of the entire garden bed is the thickest, made up of things like decaying logs or branches. The next layer is compostable material such as grass clippings or straw. Layer three is compost. And all of those layers are topped with soil.
Over time, the bottom layers break down and create a rich humus that continuously increases soil quality, provides your plants with nutrition, and helps balance heat and water retention.
The benefits of a keyhole garden
First up, keyhole gardens equal less work overall as the layers of composting organic matter cut down on the watering and feeding most gardens demand.
Keyhole gardens are also perfect for a small yard, as the keyhole access makes it easier to weed, feed your soil, and harvest vegetables. And keyhole gardens are a good option for anyone with mobility issues or a bad back as there is no prolonged crouching, bending, or reaching involved. (Thanks, keyhole!) They’re also ideal if you have a yard with poor soil.
Live in a hot, dry, or warm climate? “A keyhole garden’s raised bed keeps the soil moist all the way through for a healthy growing environment for plants and veggies,” says Mardueño.
Why are keyhole gardens a big trend now?
In the past, many green thumbs opted for the standard raised bed. But when the pandemic started, people seemed to want to live a more self-sustaining life that includes garden-fresh veggies.
“People likely found that keyhole gardens were not only affordable and a less labor-intensive method of gardening, but they could be a creative addition to a yard,” says Wells-Barrett.
How to build a keyhole garden
First, find a place in your yard and measure out your keyhole garden based on your arm’s reach from the keyhole center. Keep in mind some people build multiple keyholes rather than one large one.
Next, decide on what material you want to use to build your barrier wall. Traditional keyhole gardens are often created with a stone retaining wall. But they can be built with any material strong enough to support the layers of organic matter—think stone, brick, or treated wood (just use a plastic liner to prevent rot).
The barrier wall should be about 2 to 3 feet tall. Once that’s built, construct your compost pile in the center of the garden. The cylinder should be made out of a material that drains easily and lets worms pass through. (Fencing wire is a good option.) And the tube should be about 12 to 18 inches taller than your growing area as an active compost pile needs room to heat up and break down.
Finally, add your four layers to the bed and plant away!
How to keep your compost pile healthy
When you create your compost pile, go for a roughly 3-to-1 ratio of nitrogen to carbon-rich materials to help jump-start the natural decomposition process. Nitrogen can be found in food scraps, fresh grass clippings, or animal manure. Meanwhile, carbon is hiding in raked leaves, straw, or shredded newspaper.
As you water and turn your compost pile, the nutrients and water will drain into the growing space surrounding it.
“Your compost pile is healthy when it’s as moist as a wrung-out sponge,” says Wells-Barrett. If your pile is wet or smelly, add carbon. If your pile is too dry and not decomposing, add nitrogen, and you’ll be well on your way to fresh veggies with minimal effort soon enough.