In the Southwest, where soils are often poor and rain is not always reliable, the most productive way to grow vegetables is in a raised bed where you have complete control over the quality of the soil and the water your garden receives. With a few simple steps, a raised bed will provide you with luscious vegetables for many months of the year.
Raised beds can be made of water-resistant wood like redwood, cedar, or other sturdy untreated lumber. Treated lumber may contain chemicals that could be detrimental both to your vegetables and to you. You can also build raised beds out of concrete block or other sturdy materials.
Raised beds should be a minimum of 8 to 10 inches tall to accommodate the root systems of most vegetables, but may be built as high as 3 feet. Finished beds should be wide enough to permit you to reach to the middle without walking on the soil; that's usually 3 to 4 feet. Fill raised beds with a rich combination of mulch, compost, high quality topsoil, such as Miracle-Gro® Moisture Control® Garden Soil, and slow-release fertilizer, such as Miracle-Gro® Shake 'n Feed Tomato Fruits & Vegetables Continouous Release Plant Food Plus Calcium. As you remove old vegetables and plant new, add a 4- to 6-inch layer of compost or mulch twice a year to reinvigorate the soil.
You can grow almost any vegetable in a raised bed that you can grow in the open ground and you can use more "intensive" practices like the famous square foot gardening technique. Even vining vegetables like cucumbers and melons can be grown in raised beds with a trellis or cage to keep them clear of the ground (which also helps keep fruit clean and free of rot).