Raised bed gardening is a simple technique that may improve the health and productivity of your garden while bringing the soil up to a comfortable working level. Raised beds have better soil structure and drainage, which warms the soil earlier in the season, giving you a head start on spring. Whether for aesthetics or accessibility, modern gardeners are rediscovering the centuries- old technique of raised bed gardening for their vegetables, flowers and shrubs.

Raised Ground Beds
The simplest form of raised beds are flat-topped mounds, usually 6" to 8" high, which require no materials other than additional soil. Bring in additional soil or excavate 3-4" of soil from pathways between beds. Whether you dig out your pathways or not, be sure the access areas around the raised beds are at least 24" wide.

Decide first on the size of your raised ground bed. If you are able to reach only one side of the bed, the maximum width should be 2½ feet. If you have access from both sides, the bed can be up to 5' wide. Length and shape are entirely up to you.

To make the bed itself, add 4" to 6" of compost or enriched soil to the existing area, and thoroughly till it into the underlying soil. enrich soil with peat moss or composted manure. Take the tilled soil into a flat mound about 8" might, with sides that taper up at a 45-degree angle. Then let the soil rest for a week or two before planting. Avoid stepping on the mound and compacting the soil or breaking the sides. As the season progresses, the soil will settle, but the mound will remain. Once created, raised ground beds need only minor reshaping with a rake at the start of each season.

Supported Raised Beds
Edging your raised bed places an important barrier between your garden and the lawn, the biggest source of perennial weeds. Some gardeners also leave a 4" border of bare or mulched soil around the bed to make mowing easier. The frame, whether weed, stone, brick or plastic, adds a neat touch.

When deciding on the shape and size for a supported raised bed, keep in mind that some edging materials only allow angular corners. Prepare the soil as before, but place the frame around the bed before raking the soil into shape. To make a wooden frame, cut pieces of 2" x 6" pressure-treated lumber. Railroad ties, unless extremely well weathered, allow creosote to escape into the soil and air where it can damage sensitive plants.

Turn the long boards "heartwood in" so if they warp, they'll curve slightly outward at the middle. Secure the corners with decking screws. Remove or add soil as needed to make sure the frame is sitting level. Once the frame is in place, spread the soil even with the top. Now you can plant right to the bed's edge and have a larger growing space than in a raised ground bed of the same area.

Containerized Raised Beds
A raised bed with 10" to 12" walls offers more protection to plants in high-traffic areas near sidewalks or in curbside gardens. In paved areas where reflected heat can stress plants, raising a bed to 1 or 2 feet can reduce heat. Raised beds with even higher walls maximize physical accessibility and reduce maintenance. For most wheelchair users, 27" is a comfortable working height, but you can custom build your own plants to any height. Choose the wide to match your arm's reach.

To make a planter 27" high, place 2" x 8" and 2" x 4" boards horizontally, with 2" x 4" boards vertically for reinforcement, especially at the corners. Build the sides first, again turning the boards "heartwood in." Use decking screws to attach vertical reinforcing boards and to join the corners. You can make a sitting ledge by attaching a 1" x 4" board flat on top of the frame, extending it over the sides.