Arizona's long growing season and mild winter makes it ideal for growing vegetables. While most areas have one cool-weather crop season and one warm-season crop season, Arizona has two cool-weather seasons plus a warm-weather season. Plant cool season crops in late August for harvest in January and in November to harvest through March. It is possible to grow vegetables 365 days a year in Arizona.
Prepare the soil. Dig up the vegetable bed to a depth of 2 feet if this is the first time you are planting. Add a 4-inch layer of gypsum to the bed. Arizona soil is alkaline and so is the water. The gypsum counteracts the alkalinity.
Add a 4-inch layer of compost to the soil. Arizona soil is low in organic material and the natural vegetation of the desert is sparse. The climate is dry, so it takes longer for decomposition to take place.
Remove any rocks. Punch through caliche, a hard calcium carbonate material commonly found in Arizona. Caliche prevents the soil from draining properly. It may be necessary to rent a jack hammer to break up a large deposit of caliche.
Rake the bed smooth. Water with about 1 inch of water. The water will make high and low areas more apparent. Level out the bed.
Plant the vegetables. Plant beans 3 inches apart, corn 6 inches apart, tomatoes, green peppers, eggplant and squash 3 feet apart. Mound the soil in a ring 1 foot away from the stem of the plant to form a well.
Fill the well with water. In the hot ,dry summers watering will be necessary every other day. In the temperate winter, watering may be necessary only once a week. Deep watering encourages the vegetable roots to penetrate the soil farther.
Fertilize twice as often as package directions with a water soluble fertilizer diluted to half strength. The extra watering required in Arizona washes away fertilizer, making it necessary to replace it more often.
Water for an hour once a month to flush accumulated salts out of the soil. Arizona's water is high in dissolved minerals. The deep watering moves them away from the plant's roots.
Provide afternoon shade for the vegetable garden during June, July and August. Those months often have daytime temperatures of more than 100 degrees F in Arizona.