So, how are your gardening plans going? If you want to grow outdoors but whimper at the prospect of all the bending and kneeling with a traditional or even a container garden, why not consider a keyhole garden?
A keyhole garden is a raised circular garden with a compost center. If you’ve wanted to compost but don’t want the extra work or have the space, the keyhole garden design is the perfect solution.
At the center of the circle is a cage to hold compost.
How It Works
- Build up a growing bed using materials to assist with drainage, hold water, and enrich the soil. The more biomatter the better.
The Keyhole
Depending on the size and shape, it can be hard to reach every part of a raised bed garden. Besides the compost center, a keyhole garden has an open section which allows direct access to the compost and the inner part of the garden.
- Water the compost column only. Water and nutrients flow down a slight slope into the soil.
- Plant miniature varieties of veggies, herbs, or flowering plants to maximize yield.
- Tend the garden as usual – minus the aching back and knees part.
- Harvest a whole lot of produce!
Because of the close proximity of plants in a nutrient-dense environment, a keyhole garden can produce 2 – 10 times more than a traditional garden. According to the Illinois Extension, just 3 gardens were able to supply one family of 10 with a year’s worth of veggies.
Origin – Filling a Crucial Need
The keyhole garden was developed in the 1990s in Lesotho to address several challenges:
- An epidemic left too few able to farm, making nutritional food in short supply.
- Many elderly were willing but physically unable to manage traditional gardens which required a lot of effort to keep properly watered.
- The soil was nutrient-poor.
- The climate is arid, drought-prone.
A true recycling/repurposing solution, the garden design:
- was high enough off the ground to enable the mobility-challenged to easily tend crops
- kept out animals
- required less water
- saved the cost of purchasing supplies
The website Help Lesotho gives the full account and shows the results – some seriously proud and happy grandmothers! Grey Power!
Design Material and Benefits
Good use was made of what was freely available, no need to spend money. Materials which could be readily obtained:
- crushed soda cans served for drainage, and the metals leached into the soil, supplying needed minerals
- large stones or bricks for the wall to hold the soil and slow moisture loss
- long sticks wrapped with fabric and held with strong string to create a compost column
- soil, sand, ash, manure, straw
- compost
Specifications of a Keyhole Garden
- Shape: Traditionally round, other shapes are used
- Diameter: 6 feet or less
- Height: 2 – 3 feet tall
- Wedge: 2-foot opening tapering towards the center
- Compost column: 1 -2 feet taller than the garden. The only part of the garden that’s watered.
Naturally, the practicality of the design caused the keyhole garden to sprout around the globe. And for kits like the Vita cascading, tiered garden with the compost column at the back or some creative designs on Pinterest.
Build a Keyhole Garden
Check out this video by Green Shortz DIY which uses the hügelkultur method to build a backyard keyhole garden out of concrete wire, rusty metal, biochar, bricks, clay, and soil. It’s definitely not a simple gardening technique to start; but you may agree that the end result is worth the sweat and achy-muscle equity.
Metals and Plastics and Toxins! Oh My!
Bisphenol-A. Fly ash. Phthalates. Heavy metals. Preservatives. Lookoutohnoalarm
I was going to do a whole section on cautions about toxins leaching from scavenged materials into the soil. But the scientific literature shows minimal leaching and the EPA has lots of regulations to prevent leaching and safe use of toxic materials… If someone needs research conducted on what the scientific literature says, drop me a line. But for this article, I’ll leave it at this:
Do your research, count the non-monetary cost, and happy building.
Tips for a Great Keyhole Garden
Bobvila.com recommends
- using 3 – 5” of rock or gravel for aeration
- grading the soil down from the compost column to improve nutrient flow
- Keep the compost content level with the soil line
- rotate crops annually – shallow vs deep rooters
- Start a fresh compost cage every 3 to 4 years
- Keep the top of the compost pile moist
- Plant where there’s a good 6 hours of direct sunlight
- Use compact plant varieties to maximize planting space and variety
These are actually the basics of a good keyhole garden. I’ve included the links to these sites so you can have a more thorough learning experience.
Keyhole Gardening in the Mid-Atlantic
As much as I loved the idea, I was brought up short by the obvious. Arid is not a word generally applied to our corner of the world. Could a technique developed for a water-poor environment flourish in the humid and sometimes soggy Mid-Atlantic?
Happily, the answer is yes.
What the Expert Says
I asked Neith Little of the Maryland Extension if there is a danger of the soil becoming overfed in our wet and humid growing months. She replied that, although rain does make compost decompose faster, the relatively low nutrient concentrations (<1% to maybe 4% of nitrogen, phosphorus, and potassium by weight) won’t burn plant roots the way a concentrated fertilizer containing 40% nitrogen could.
Then she added, “However, nitrogen is water soluble. This means that when it rains, nitrogen tends to dissolve in the water and leach with it below the rooting zone, where plants cannot get it. So it might be worth checking the plants for nitrogen deficiency symptoms (yellowing of older leaves).”
“The good thing, though, is that the keyhole garden design will improve drainage and help prevent the soil from becoming waterlogged, which can damage plant roots.” she concluded.
These days, you can even buy a Keyhole raised garden bed from Amazon.
The Keyhole Garden in Your Future
Clearly, a keyhole garden Ticks All the Right Boxes. Apt descriptions:
- permaculture (sustainable, regenerative)
- economical (no need to purchase fertilizer, repurpose materials)
- green: food waste goes into the next crop of food, not the landfill. And you don’t have to drive to a compost location
- hugelkulter twice
- no-till gardening
Is a keyhole garden in your future? Checkout the ideas on Pinterest for inspiration, look for local examples, read up, and enjoy the easy-access, low-maintenance happy marriage of composting and permaculture that is a keyhole garden.