Raised beds are ideal for sites with very little or very poor soil and for gardeners with physical disabilities. Additional benefits as well as drawbacks of raised beds are listed below. Benefits • often require less time and labor to establish than in-ground beds • less vulnerable to disturbance from pets and children • do not require gardeners to bend down • tidy aesthetic
Drawbacks • can be relatively expensive to establish due to cost of siding and soil • soil temperatures fluctuate more than in-ground beds • soil tends to dry out more quickly than in-ground beds • limited exposure to surrounding soil biology
Siding Raised beds can be made of wood, stone, pavers, bricks or cinder blocks. Avoid using tires and pressure treated wood, as they contain chemicals that leach into the soil. It is also best to avoid metal siding, as metal heats up during summer, raising soil temperatures and stressing plants. To build a simple, 4x4 ft. wooden raised bed, see the instructions below.
Materials • Cardboard and newspaper (more is better!) • 1/2 cubic yard of good garden soil • (2) 2” x 12” x 8 ft. lumber boards, cut in half • (8) 21⁄2 in. nails • Sandpaper
Prepare the site: Choose a flat area or level the area, then use the cardboard and newspaper to create a weed barrier. Lay two to three layers of cardboard over the bed’s intended location and at least two feet outside of where the bed will be placed. Overlap the cardboard’s edges by at least four inches. Cover edges with two to three layers of newspaper and seal by wetting the entire area. This is called sheet mulching. It provides a temporary weed barrier, as the cardboard and newspaper eventually breaks down.
Assemble the bed: Sand the ends of the lumber boards to avoid splinters then assemble the bed by laying the lumber boards together so that crowns face inward and the boards are off-set. Nail the boards together and place the bed on top of cardboarded area. Fill the bed with garden soil, mix in compost, then mulch and plant.
Tip for cheaply filling raised beds: If your raised bed is 24 inches high or taller, you can save money on soil by filling the bottom six inches of the bed with unfinished compost. First, place a layer of leaves, twigs and branches at the bottom of the bed to trap air, then cover with a few inches of raw compost and a second layer of leaves and twigs. By the time plant roots reach the bottom of the bed, the compost will have broken down into soil.