Everyone loves a good bargain, especially if it’s buy one get one free. That is exactly what you get with keyhole gardening.
Keyhole gardening combines two concepts – composting and raised beds – into one garden. It was used often in African countries where there was poor soil and few resources to build a raised bed. Keyhole gardens are typically constructed of various natural or found materials and incorporates composting that will improve the soil conditions in the garden bed over time.
The term keyhole itself comes from the aerial view of the shape of the circular bed with a notched cutout that provides access to the smaller compost center. This central compost pile continues to feed nutrients to the surrounding garden. The notched access to the compost basket is ideally located on the north side to maximize the planting area that receives the greatest amount of sun exposure.
Get creative with the exterior walls of your keyhole garden. You can add texture to your landscape by using rocks, pavers, branches, wood or even plastic. Depending on your needs, the garden can range in height from just a few inches to waist high. The taller the garden, the more accessibility you’ll have, which can be handy if you have difficulty kneeling and bending. Generally, keyhole gardens are 6 feet in diameter, so the garden space is accessible from the perimeter.
When starting a keyhole garden, line the bed with cardboard along the bottom and walls. This will help hold materials in the garden and also serve as a barrier to prevent weeds from growing. Next, fill the bed with compostable materials rather that straight soil. Layer newspaper, sticks and straw, followed by lawn clippings and aged manure. Top this with about six inches of soil. The soil will provide space for plants to grow as the materials below the soil break down.
The interior compost basket usually is 1 to 2 feet in diameter and plays a key role in a keyhole garden as it’s where you’ll feed and water your garden. Small amounts of compost you acquire daily, such as vegetable scraps, dryer lint, coffee grounds and eggshells can be deposited in the center compost basket. As you add water to the compost basket, the composted nutrients will seep into the main area of the garden.
A keyhole garden is great for warm-season plants such as beans, eggplant, peppers, pumpkins, squash, tomatoes, watermelon and zucchini. Gardeners also can plant cool-season veggies such as beets, carrots, chard, garlic, kale, lettuce, onions, peas, radish, spinach and turnips. For those who enjoy herbs, consider planning basil, oregano, catnip, chives, cilantro, dill, fennel, lavender, lemon balm, lemon verbena, marjoram, mint, oregano, parsley, rosemary, sage and thyme.
If you prefer to grow ornamentals, a keyhole garden will work for those, too. Some considerations include lantana, milkweed, zinnias, daisies, ice plant, coleus, petunias, begonias, geraniums and nasturtiums.