UGC Member Barry Vokes recently attended a workshop on Keyhole Gardening presented by Dr. Deb Tolman and sponsored by the Bell County Master Gardener Association – in Belton. Here are his notes:
Her keyhole gardens do not use any soil at all but some finished compost goes on top as the initial planting medium. The key is gathering all the needed materials before construction begins, and that is crucial. Having a pile of nitrogen inputs and a pile of carbon inputs on hand, along with lots and lots of cardboard and etc. makes it much quicker and easier to build the bed in layers.
Construction requires bales of wet (saturated) cardboard. Dr. Deb soaks each piece in a 55 gallon drum of rainwater for about five seconds before placing it in the bed. That saturates the cardboard and makes it easy to work with. Put the cardboard into the bed in thin layers and separate each layer with greens, maintaining a 3:1 ratio of browns to greens. Sprinkle grass clippings on in thin layers. Add layers of newspapers and make sure they are fluffed up (e.g., shredded) so they do not compact. Add as many old phone books as can be found, and no need to wet them before tossing them in. Magazines are fine too, but tear off the covers and make sure they are not too thick. Thoroughly wet each layer as the interior of the bed is built up. Junk mail (shredded) is a perfect addition. Chicken manure is good, as is cow manure, but no horse manure. Donkey manure is fine.
A well-constructed keyhole garden can be expected to lose one foot of height within two weeks. A keyhole garden is a terrific place to grow two or three fruit trees such as apricots or plums. Berries are good too (except blueberries, of course). You plant trees at an angle, let them hang over the sides and prune off the inside parts. Near the center you plant something that grows tall. You cannot put too much water on a keyhole garden during initial construction. Use lots and lots of water. After that, it will be very water-wise. You may only need to water two or three times during the summer. One keyhole garden will grow over 70 tomato plants. You plant intensively in a keyhole garden. Some plants will grow tall and others will hang over the sides. Some will send runners out 30 – 40 – 50 feet.
If the keyhole garden is properly constructed, all the cardboard, phone books, newspaper and etc. will turn into rich, black soil within six weeks. Be sure to make the center basket one foot higher than the sides and slope the soil down from the center to the sides. The plant roots will grow toward the nutrient source in the center basket. Put all your vegetable kitchen scraps in the center basket and keep it wet.
Coffee grounds will control fire ants in a keyhole garden. It does not kill them but for some reason not fully understood, they don’t like coffee grounds and will move to a location outside the keyhole garden. Hot manure is fine to use during construction – but not too close to the surface. Don’t use horse manure because of the likelihood that the horses were fed hay with pesticides/herbicides in it. Deb Tolman has decided not to grow food in her 10 or so keyhole gardens during the summer months, starting this summer. She says it just is not worth it. She suggests a spring garden and a fall garden, with the keyhole gardens left fallow in the interim between seasons.
Deb Tolman is an excellent speaker. She lives in a converted oat bin (10’ X 10’) without A/C on the Starnater Ranch just outside Clifton. It was well worth the time invested in going to hear the presentation. The overall theme of the talk was drought gardening in Texas, of which keyhole gardens are a subset. I hope this brief summary is helpful.