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The Garden Scoop

Keyhole Gardens

In recent years, a new gardening phenomenon has gained popularity in the US, but it gets its roots abroad.  Keyhole gardening is a technique that was developed in Africa, for use in dry, arid climates with low soil fertility.  It has proven to be such an effective, sustainable method of small scale plant production that US gardeners have readily adapted across the country.

A keyhole garden is a form of raised bed, typically circular in design, that employs active composting to replenish and build new soil.  The centerpiece of a keyhole garden is a “basket” that the gardener continually deposits compost and water into.  The compost basket extends above the raised bed allowing water and nutrients from the compost to enter the soil, replenishing it continually as compost is added and decomposes.  In order to access the basket, a notch, similar to a missing piece of pie, is added which creates a shape similar to a keyhole from the bird’s eye view.  These compact, efficient gardens have been publicized for their reduced water use and increased productivity when compared to conventional gardening methods.

In recent years, this clever design has been used throughout the world.  It is attractive and very productive with no need for added fertilizers, making it quite sustainable since everyday compost can be used to fuel the system.  Keyhole gardens can be densely planted to maximize the amount of vegetables grown in a small space.

Humanitarian charities in Africa were the forerunners in keyhole garden design.  It’s simple and sustainable design features arose from necessity since fertile soil and water are quite limited in many areas.  However, food scrapes and gray water (from household chores such as washing dishes) are readily available.  Three of these gardens, approximately 6 feet in diameter, can supply an African family of 10 with vegetables for the year. 

Keyhole gardens have subsequently been adapted for other areas of the globe that experience similar dry climates, low soil fertility and scarce resources.  They have rapidly gained popularity in arid areas in the US, such as Texas and Arizona, and have been applied in more humid regions to serve folks looking for cheaper, more sustainable gardening methods.

Although you may purchase kits online nowadays, the originators of this design used many types of recycled materials.  So, you may already have everything you need laying around the yard.

The outside wall of the garden can be constructed from anything that will hold back the soil and provide some structural support.  Rocks or recycled bricks are excellent wall building materials, although something as simple as some old lumber will work. 

The composting basket in the center, typically 1 ½ feet in diameter, is commonly made from chicken wire or woven wire.  However, you can use any material that will hold back compost and still allow water to permeate into the soil.  I have seen some interesting and effective designs using materials as simple as a “tower of sticks” to create the basket.  No need to get fancy. One of the greatest attributes of keyhole gardening is the sustainability and use of recycled materials.

The ultimate form of recycling in keyhole gardening is the use of compost.  To initially build soil in the garden, a wide range of recycled materials, along with some soil, are added in layers.  The lowest layer should consist of larger materials that allow for drainage, such as sticks, old broken pots, rocks, and tin cans.  Keep building the layers including things such as newspaper, straw, manure, wood ash, leaves and mulch.  Complete your soil building layers with the best materials you have available, such as finished compost or topsoil. 

If you are interested in checking out keyhole gardens in action, the Vermilion County Master Gardeners have installed several at Douglas Discovery Garden in Danville.  In addition, the Master Gardeners are hosting the annual Antiques in the Park event today, from 10:00am to 4:00pm at the Douglas Discovery Garden.  This event includes a plant sale, food vendors, live music, local products for sale, a Master Gardener Q&A table and, of course, antiques.  Please come out and join the Vermilion County Master Gardeners for this family friendly event to enjoy the beauty of the Douglas Discovery Garden and learn how to set up your own keyhole garden.