What is a keyhole garden? I’ve been asked this exact question countless times when discussing permaculture with fellow gardeners. The simplest answer I can give is that a keyhole garden uses a design that allows gardeners to maximize their growing space. This answer usually doesn’t quiet inquiring minds, so allow me to further elaborate the benefits that two different keyhole garden styles have to offer.
Why a Keyhole Shape?
Keyhole gardens get their name from the thin walkway that leads into the garden, opening up into a small central circle in. When viewed from above, they resemble old-fashioned skeleton keyholes. This shape is one of the key factors (haha!) that helps this garden type to be such an excellent space maximizer.
How many walking paths do you have in your garden? Consider how many delicious things could be growing in that space instead Even if you keep your paths thin—let’s say 18” wide—that’s still a lot of wasted growing space that could be put to better use.
A lot of gardeners, myself included, plant in straight or semi-straight rows. There are benefits to this approach, such as allowing more space between plants or to help control water runoff from rainstorms. If you’re aiming for more available garden space, however, straight rows aren’t the way to go.
I won’t bore you with the math here, but imagine a long, straight garden bed. Let’s say twelve feet long. Now, imagine bending that bed into a “C” shape. By doing this, you’ve eliminated the majority of the necessary walking from the former straight bed.
Instead of a walking path that spans the entire edge of the twelve-foot bed, you’ve wrapped the edge around a much smaller space. You’ll now have access to the entire edge of the same garden bed, but in a fraction of the space!
When planning any garden, orienting it with the sun is always an important design aspect. Keyhole gardens are no different. It’s generally best to have your walkway facing the south, so it’ll receive the best sunlight. Obviously, specific situations may cause you to face it a different direction, but, that’s ok too! Being aware which way is south will help you plan it out better.
A south-facing keyhole garden should have smaller plants, and more frequently harvested plants near the garden’s interior. This will keep them more accessible to harvest. It’ll also allow taller plants to grow behind them without blocking their sunlight. Growing crops (especially slightly taller ones) that are more tolerant to the afternoon sun and heat should be planted in the west.
This will help provide shade to shorter sun- and heat-weary crops that might otherwise bolt too early.
A Basic Keyhole Garden
Making a basic keyhole garden is really pretty simple. First, select your site and measure out a circle that’s about 6-8 feet wide. Keep in mind, that 3-4 feet is about the extent of our reach. You want to be able to reach the outer edge of your garden from the walk path. Make a walk path that’s at least 18” wide. This will end in a small circle big enough for you to turn around in comfortably.
Next, mow down any existing plants.
You can leave whatever plant matter you mow: it’ll become a thin layer of mulch at the bottom of your bed. I would suggest sprinkling some blood meal and a bit of aged manure down next, but this isn’t necessary. If you want, you can rototill the ground (before or after the manure and blood meal). If your soil is fairly decent, I would personally skip this step. Rototilling violently breaks up and destroys the tiny life (mycelia, worms, etc.) in your soil.
Lay down some un-dyed cardboard next, to suppress weeds. Use enough cardboard so it goes past the edge of your planned garden by at least six inches. This overlap will slow weeds from crawling into your garden from the edges. Afterwards, lay down rocks or bricks around the edge of your garden and walk path. The taller this rock or brick edge is, the more soil and compost you can add later.
Fill your bed with compost, peat moss (or coconut husks to be more eco-friendly), mowed leaves, grass clippings, aged manure and/or soil. You don’t need all these to fill your bed, but your garden will be more plentiful if you do!
That’s it! Now, plant your crops and orient them according to their size, how often they are harvested and their tolerance to sun and heat. I explain all this later on in this article.
Ultra Keyhole Garden
Another keyhole garden style is a raised circular bed with a compost basket in the middle. This style was designed by humanitarians in Zimbabwe in the 90’s. It was designed to help impoverished people build a simple permaculture garden that could feed them all year. This garden’s height allows for moisture-retaining organic matter to be used, which is perfect for dry, arid climates. It also provides an area to sit on as you work.
Begin in the same way as the basic keyhole garden. Measure your circle and mow down existing plants. If you want, you can add some blood meal and aged manure, then lay down cardboard to suppress weeds.
Some designs include a basket in the middle for composting. This is to allow easy access to compost to spread in your garden. Compost material and water will also run out of this basket and spread naturally. If you include this type of basket in the middle, it’ll need to be made of a material that allows water to run through it easily. Willow, wicker, and chicken wire are good options.
Now, you can build up your outer edge and walk path with stones or bricks. The taller you build it, the more organic material you’ll be able to put under your bed to retain moisture. If you’re good at stacking bricks and stone, than you may not have to mortar it together. I’d suggest mortaring a fairly tall raised bed to extend its longevity. It’d be a shame if you knocked over your wall with a wheelbarrow, or if some other accident caused it to topple over.
Fill ‘Er Up
Once your wall is complete, you can begin filling it with organic matter. Add a layer of sand at the bottom to help with drainage. If you want, you can also put rocks or even old cans/bottles in the bottom to help with drainage too. A layer of about 2-3 inches should be just about right.
Next, add the moisture-retaining layers. These should fill 1/3 – 2/3 of your available raised bed area. I’m a big fan of Hugelkultur raised beds, so I suggest adding lots of old rotting wood, broken-up sticks, and branches. This wood will break down and eventually turn into soil. In the meantime, it’ll hold moisture and help create the perfect environment for mycelia to grow. Mycelia are important for creating healthy soil!
You can also add a thick layer of hay or straw at this point. (I always suggest hay, as it’s supposed to have fewer seed heads.) Hay can be added on top of your hugel layer, or can even replace it. If your walls are tall enough, you may even be able to put an entire, non-broken-up bale of hay down, and still have plenty of room for more organic matter and soil. Hay/straw will break down and create the same effect as the rotting wood and branches—it just won’t last as long.
Next, add aged manure, potash, compost, coconut husks and/or soil until you reach your desired soil height.
Now you’re ready to begin planting! Once your crops have begun poking out, you can add a 2″-3” layer of hay around them. This will further hold moisture and stop the sun from drying out your soil.
As the seasons go on, you can continue to add more compost and organic material on top to make up for the soil settling and moisture-retaining layer breakdown.
What to Plant
The type of keyhole garden you build will determine which crops you can grow. Traditionally, keyhole gardens are mainly used for leaf and root crops. Soil depth is one of the main factors for what you’ll be able to grow successfully.
If your keyhole garden only has 12”-18” of soil available, stick with crops that have shallow roots. These are the more commonly grown crops in keyhole gardens: arugula, garlic, lettuce, spinach, radishes, onions, strawberries and/or potatoes. Brassicas such as Brussels sprouts, broccoli, kohlrabi cabbage, and cauliflower work well too.
If you have deeper soil that’s 18”-24” deep, you can plant deeper-rooted crops. These include: pole beans, snap beans, beets, peas, kale, chard, carrots, peppers, eggplants, cantaloupe, turnips and/or cucumbers. Plant pole beans and cucumbers near the edge, so you can attach a trellis for them to grow on. This could also double as a western sun break.
Plants for Super-Deep Soil
If you have super deep soil that is 24”-36” than you can grow: tomatoes, lima beans, okra, asparagus, rhubarb, winter squash, sweet potatoes and/or watermelon. Most keyhole gardens aren’t this deep, but if you build a raised bed and have hugel logs or a straw bale at the bottom, these should grow well.
Plant species such as radishes, onions, and carrots closer to the outer edge, since they only get harvested once. This leaves room for the more frequently harvested crops near the center.
I’d personally recommend planting vines like watermelon, cantaloupe and (even) cucumbers somewhere else. They can be grown in a keyhole garden, but they (and you) will be much happier if they are able to grow unimpeded and not steal all the sunlight from your other crops. If you just really want to grow them in your keyhole garden, plant them near the edge and train them downward away from the walk path.
Another design people like to add is planting flowers, herbs, or shrubs in the margins. If you made a square around your keyhole garden, the triangular spaces on the corners are the margins. These are excellent places to put pollinator-attracting plants or medicinal herbs such as comfrey, rosemary, or lavender.
If you find that you really like this garden style, you may want to try making a mandala keyhole garden. This is essentially a bunch of keyholes combined together, to make a very aesthetically pleasing vegetable patch. Mandala gardens are wonderful to walk through, and a very efficient use of your garden space. If you’re interested in creating one, I’d recommend looking up mandala keyhole garden to get some design ideas!
Keyhole gardens really are a fantastic way to put a lot of vegetables into a much smaller area. Being efficient with our garden space is a commonly overlooked aspect of garden design. By redesigning our garden layout, we can considerably increase the amount of produce we harvest each season.
Hopefully, if nothing else, I’ve convinced you to think about your available garden space and how to use it in a more efficient and visually pleasing manner.