Answer: Roses in containers can be transplanted from January through April in the low desert, which gives them time to develop root systems before the heat (the sooner the better). Roses require excellent drainage and a rich soil. Use a 50-50 mixture of good potting soil and compost/peat moss. Mix a rose fertilizer or a product like Miracle-Gro (15-30-15) into the planting hole. Water thoroughly and keep soil consistently moist, but not wet. Fertilize every six weeks or so, or use a slow-release fertilizer.
Summer is considered a dormant period for many of the non-native plants that grow here, such as roses. It's best not to "force" them to produce at this time with fertilizer. It stresses the plant and may cause fertilizer burn. Provide protection from the hot afternoon sun and strong winds, especially for containers. Water slowly and deeply, and let the water leach salts past the root zone. "Sprinkling" with water lightly and frequently allows salts to accumulate in the soil, burning roots. Fertilize again just as weather cools in the fall. I hope this info helps.
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