Prepare the area. Select a location in your yard that receives the proper amount of sunlight for the plants you intend to grow. Clear the area of weeds, plants and turf.
Outline the shape of the bed you intend to build with a piece of chalk. Draw an outline 4 feet long by 4 feet wide for a basic, square-shaped bed appropriate for many garden plants. Dig in vertical strokes from one side of the bed outline to the other. Dig into the soil deeply enough to bury half of one of the boards you are using to make the frame of the bed.
Cover the bottom of the outlined area with a weed-control fabric from your local garden supply store. This prevents weeds that may exist in the remaining soil from becoming problematic in your new raised bed.
Place a layer of wire mesh over the weed control fabric to prevent gophers or burrowing pests from entering your raised bed.
Cut or have 24 pieces of 2-by-4-inch lumber cut to 4 feet long. Cut or have four pieces of 2-by-4-inch lumber cut to two feet long.
Place four of the 4-foot long pieces onto a corresponding line on the chalk outline to create a frame for the bed. Overlap the corners to create a smooth, square corner on each side.
Place a 2-foot-long piece vertically into each corner on the inside of the bed. Nail the 4-foot-long horizontal pieces into the 2-foot-long vertical pieces to hold them all together.
Place one of the 4-foot-long pieces horizontally over the initial frame of any wall. Attach this piece to both 2-foot-long vertical pieces on that wall by nailing through the 2-foot vertical pieces into the 4-foot horizontal piece from inside the bed. Repeat this process for each remaining piece of 4-foot-long lumber, placing six pieces of lumber onto each wall. This should create a 2-foot-high wall on each side.
Fill the raised bed with a soil mixture of your choice. A 4-by-4-foot raised bed that is 2 feet deep requires 32 cubic feet of soil. Fill the area around the outer area of the garden bed until the bed is halfway buried around its perimeter.