Phoenix, Arizona, is known for its mild winters and hot summers, and all that warmth and sunlight makes Phoenix an ideal place to grow roses. Although growing roses in a desert environment isn't difficult, the extreme heat and punishing summer sun require a few extra precautions. As long as your roses get adequate water and fertilizer and a bit of protection during the hottest part of the year, you should be rewarded with big, sunny blooms.
Plant roses where they will be exposed to morning sunlight. Roses need six hours of sunlight but should be protected from the hot afternoon sun. During much of the year in Phoenix, the sunlight and heat can be too intense. If you don't have an area that provides afternoon shade, plant the rose under a tree, where it will be in filtered or broken shade during the afternoon.
Water the roses regularly. Although roses are fairly drought-tolerant, they will benefit from plenty of water in Arizona's arid climate. The higher the temperature, the more water they will need. Be sure the soil drains well so the roots don't sit in soggy soil.
Spread 4 to 6 inches of organic mulch, such as pine needles, dry grass, chopped leaves or small bark chips, around the rose bushes to keep the soil cool and moist. Replace the organic mulch every spring. To give the plant an added boost, spread an inch of compost under the organic mulch. Leave a 3-inch ring of soil uncovered immediately around the trunk, because mulch buildup against the trunk can harbor warmth and moisture that can invite pests and disease.
Feed roses weekly with a fertilizer especially for roses or an organic fertilizer, such as fish emulsion. Read the label on the fertilizer package, and follow the directions closely. During the heat of the summer, when the temperature reaches 100 degrees, dilute the fertilizer to half strength, because too much fertilizer can burn the foliage when the temperatures are high. Fertilize rose bushes in early evening so the fertilizer can be absorbed before the heat of the next day. Always water deeply after fertilizing.
Prune roses by at least half their size in January or early February. Prune just above a leaf node, which is where leaves or buds grow from the stem. Remove broken, older canes and ones that grow across the center of the plant and leave new, green canes. Remove leaves and toss them on the compost heap. Use clean, sharp pruning shears, because dull blades can damage the canes.
Give roses a second, lighter pruning in September, removing no more than one-third of the growth. Prune spindly, uneven growth, leaving canes no larger than the size of a pencil.
Deadhead, or remove spent blooms, regularly. Otherwise, the rose will direct its energy to make hips, or seeds, instead of more blooms. Cut the spent blooms with pruners, along with a few inches of stem. Leave as much foliage as possible to provide nutrition to the plant and protect the canes from the hot sun.
Keep the rose bed neat and tidy. Pick up any fallen leaves or petals, and keep weeds pulled. Debris buildup can invite fungal disease and pests.