Problems With Potted Roses in Desert
Q: About eight months ago, I purchased several tree roses in large pots. I have already lost one, and another is close behind. They were replanted in larger pots with good mulch soil. Two of the four remaining are doing well. One has new growth with wilted leaves. The other has lost most of its leaves, and the new growth gets brittle and dies. I've provided them with good irrigation, and they don't sit in water. Soil is kept moist but not wet. The leaves turn brown and crusty on the edges, then yellow and wilt. I was told that potted roses should be fertilized at every watering (I use a rose fertilizer), and it seemed to do well with the others, but not these two sick ones. I have also given them a good drenching to make sure the salt is washed out through the holes and used bone meal, but no noticeable improvement. What's wrong?
A: It's unusual that you are having such a variety of symptoms when the conditions you are providing are the same. Are the roses all the same variety, or do you have different ones? If you have different varieties, perhaps some are better suited to the low desert than others. It sounds as if you are doing a good job of care. However, summers in the desert are extremely tough on roses, particularly those in pots.
Did you provide protection from afternoon sun? Soil temperatures in pots can reach 150 degrees F in summer. Container plants in these type of conditions benefit from afternoon shade during the summer. Stressed plants are more likely to show problems than non-stressed plants. Here are some potential reasons for the symptoms you describe:
For more information--there are several very active rose clubs in the Phoenix area. Visitors are always welcome at their meetings. Phoenix Home and Garden lists these clubs and their meeting times in their "Around Arizona" section at the back of the magazine.