Raised garden beds are a good choice for gardeners who have poor quality topsoil. The frame for the raised bed is simply set on top of the existing soil and is filled in with good quality garden loam. Gardeners in cold northern areas can also benefit from raised garden beds because soil in beds thaws out and warms up earlier in spring than ground-level garden beds.
Mark the borders of the intended raised garden bed by pounding a stake at each corner. Attach a string to the stakes, creating an outline of the new raised bed.
Remove all vegetation inside the marked area. Use a shovel to cut away sod by holding it nearly horizontal and pushing it underneath the roots of the grass. Dig out all annual and perennial plants or weeds with a shovel, taking care to remove their entire root systems.
Create a raised border along the string marker using 2-by-6 lumber. Secure the corners with corner brackets. Install corner brackets by positioning one so half of its length falls on each board to be joined and nailing or screwing into the wood. Increase the depth of the raised bed to 12 inches by stacking another layer of 2-by-6 boards on top of the first layer.
Add topsoil, compost and peat moss to the area inside the wooden border to raise the level of the soil almost flush with the tops of the wood border. Use a ratio of four parts topsoil to one part compost and one part peat moss.