Measure your available vegetable gardening space--and think small. Instead of plotting out your whole garden with room to walk between each row of vegetables, divide your space into 3-by-3-by-4-by-4-by-2-by-6 feet rectangles, allowing 18 inch paths between them. Plan and draw out the most efficient use of your space and record your measurements.
Determine the height of your boxes. Raised beds are generally between 6 and 12 inches high, making it easier for you to reach your plants. Raised beds also store warmth in the soil and let you enrich soil for vegetables with varying nutritional needs.
Purchase outdoor-grade lumber, but avoid pressure-treated lumber for vegetable beds. Improvements in pressure-treating have diminished concerns about arsenic salts that can leach into soil, but copper compounds remain a concern. Choose a durable wood like redwood, if available, or consider plastic lumber. Wood beds will last five to eight years, depending on your climate, and are easily replaced. Plastic lumber lasts even longer.
Cut the lumber to your pre-determined lengths, or have the wood cut at the lumber yard. Assemble your hollow boxes with screws at 2-inch intervals. For slightly greater stability, join the corners with angle-irons and screws.
Clear ground for the boxes. Remove large stones and debris, pull large weeds and rake smooth to a depth of 1 to 2 inches. Set the boxes in raised soil, leaving paths of approximately 18 inches between them so you can walk. Tamp boxes firmly into raked soil once you have positioned them as you wish.
Line finished boxes with landscape cloth, tacking it to the sides of each box with your staple gun. Fabric can come partly or completely up the sides of your boxes. The fabric prevents soil from washing out from under your boxes, along with plant nutrients, and provides a barrier against weeds.
Fill the beds with fresh topsoil. Add peat moss or any other amendments needed to provide drainage for your vegetables.
Add small amounts of fertilizers that are needed by specific plants. Enhance nitrogen for leafy crops--without adding excess leafiness to your tomatoes. Try a root-crop fertilizer just where you need it.