You may have seen the television commercials touting the virtues of upside-down planting containers. While it may sound contrary to nature, growing your tomatoes suspended in the air really does work. It keeps the plants far from pests and diseases that lurk in your garden soil, and it makes easy work of harvesting. Growing tomatoes in Phoenix has its own challenges because of the extremely hot temperatures, but you can successfully raise an upside-down crop in the Arizona city.
Because summer temperatures in Phoenix rapidly hit 100 degrees F (and higher), the growing season for tomatoes is shorter than other southern climates. Purchase early tomato varieties with short harvest times and that are known for thriving even in the hottest weather. In "Tomatoes in the Desert Garden," Maricopa County Cooperative Extension Master Gardener Laurel Reader advised selecting cultivars that are mature in 60 to 70 days. Varieties that are good choices for Phoenix include 'Heat Wave,' 'Early Girl' 'Solar Fire,' 'Earliana,' 'Patio,' and heirlooms like 'Arkansas Traveler' and "Mule Team."
When choosing your soil, pick one that really retains moisture to help combat Phoenix's dry climate. There are various commercial mixtures available, but you also can beef up the moisture retention of regular potting soil by adding granular polymers. The polymers absorb water and release it slowly. As the summer progresses, check your soil level, adding more if the level is more than 2 inches from the top of the bucket. Old-fashioned Living.com suggests growing a "living mulch" like basil, parsley or cilantro on top of the dirt to shade the soil and give you an extra harvest.
Tomatoes planted upside down require daily watering. The containers dry out more quickly than regular garden soil, and Phoenix's wind can dehydrate the plants. Water with a slow hose placed directly on top of the soil, and keep the water on until it starts running out from the bottom hole. When you plant your tomato, strip off all the leaves except those on the top 3 inches of the plant. Bury your tomato up to those leaves; where you removed the others, root nodes will form and make your plant stronger. Add a slow-release fertilizer made for tomatoes to your potting soil, and fertilize throughout the growing season with fish emulsion.