In June, apply one fourth cup of magnesium sulfate. Apply one fourth cup again at the end of August. Water deeply once a week or more often if necessary. Remove faded roses after bloom. Apply 3 to 4 inches of mulch to the rose beds and sprinkle a light application of nitrogen over the covering to hasten decomposition.
Roses produced during the summer are usually half the size of spring and fall roses.
Treat powdery mildew and insect-infested roses with the proper sprays. Beginning in late August, remove all weak and undesirable canes to the crown or base of the rose. Reduce the bush's top growth by one third to stimulate the fall flush of growth. Return to normal amounts of fertilizer. For higher quality blooms, apply a soluble fertilizer to the foliage every two weeks until buds show color.