Above-Ground Gardening Beds

Make Your Bed

• A 6- to 12-inch-deep above-ground bed is suitable for most plants. If a bed sits on the ground, the plants' roots can penetrate the soil beneath. That factor makes the use of shallower, 6-inch-deep beds more feasible. Twelve to 18 inches is a sufficient depth for root growth in beds setting on concrete or having a bottom. Keeping beds no more than 4 feet wide allows you to reach the center of them without walking on their soil. Make the sides of the above-ground beds with untreated wood boards, bricks or stones, depending on the materials you have available and how you want the beds to look.

Play in the Dirt

• A primary benefit of above-ground beds is improved soil conditions. So avoid using regular soil from your yard. A quality topsoil combined with equal parts of finely shredded pine bark and perlite results in good soil and good drainage. Alternatively, combine compost with equal parts of peat and topsoil. The compost provides organic matter and some nutrients to the soil mixture. Add more nutrients by mixing in ¾ cup 18-6-12 fertilizer and ½ cup dolomitic lime with every 1 cubic foot of soil mix.

Choose Your Green

• Correct plant placement helps above-ground gardens grow better and can ease maintenance chores. In vegetable beds, place tall plants or those that grow up a trellis on the north side so they don't shade out smaller plants. If a bed has a shady areas, then select plants that tolerate some shade for those locations. If an ornamental bed is viewed mainly from one side, place tall plants at its rear and shorter plants at its front. If a bed is visible well from all sides, then grow short plants around its inside perimeter and place taller plants in its center. Follow the recommended in-row spacing on each plant's seed envelope or nursery label, but also use that spacing between rows. Unlike traditional gardens, above-ground beds don't require wide rows.

Keep it Growing

• Above-ground beds require the same basic care as traditional beds. Their soil, however, may drain and dry more quickly than traditional beds' soil. So check soil moisture daily, and provide water when the soil begins to dry. A 2-inch-thick layer of mulch over the top of each beds' soil helps to retain soil moisture and can minimize irrigation needs. Weeds can invade raised beds, but they rarely become established well enough to be a problem if they are pulled as soon as they are noticed. Follow the same fertilization schedule for above-ground beds as you would for traditional beds. An application of 1/2 cup of 13-13-13 fertilizer per 4 square feet of soil each spring, followed by a 1/3 cup application of 13-13-13 fertilizer per 4 square feet of soil in midsummer, works well for many vegetable and ornamental plants.