Raised beds can help your plants--and your back--by putting plants above ground level, where they are easier to reach and safer from some of the ground-dwelling pests, such as snails and slugs. You can build raised beds without borders or you can build wood, brick or rock enclosures for your beds. A rock border helps to keep the soil in place and adds to the appearance of your garden.
Measure and mark the area where you want to build the raised bed. A typical size is 4 feet by 8 feet. Make sure the area you select receives the correct amount of sunlight for the type of plants you plan to grow. Sprinkle flour around the border of your bed area to mark the edges of the bed.
Pull all weeds in your marked area or mow grass and grassy weeds. Then, spread flattened cardboard boxes over the area inside the flour border.
Stack medium-sized rocks, 3 to 4 inches in diameter, around the border of the bed. If you plan to grow small plants, such as herbs and summer annuals, make your bed about 6 inches tall. If you plan to grow vegetables, such as tomatoes, which need plenty of room for their roots, stack your rocks higher--to 12 or 18 inches. You can even grow trees in raised beds--build the rock border as tall as 3 feet if you plan to plant a tree in the raised bed.
Fill the bed with organic materials and topsoil to create a rich growing environment for plants. First, spread a 1- to 2-inch layer of gravel, pebbles or small rocks on top of the cardboard. Then, fill the bed to the top of the rocks by spreading layers of topsoil, organic compost, peat moss, fallen leaves, grass clippings or chop up last summer’s corn stalks, dead tomato plants and other garden debris.
Rake the surface of your the bed to level it and then water it by running a sprinkler over the area for 20 to 30 minutes. You can then plant immediately.