Rose bushes are considered high-maintenance plant because they easily attract fungi and pests. But you can take steps to help prevent these problems, including purchasing rose bushes bred to be resistant to certain fungi. If you want to grow roses, always keep pesticide and fungicide on hand. If pests and fungi are caught early, the roses can be saved.
Pruning in Spring
Prune rose bushes in the spring for dead and decaying plant matter. Remove all fallen or cut plant matter, as decaying plant matter on the ground attracts pests and fungi.
For winter preparation, after the second or third hard frost, cut the canes back to about 4 feet tall. Gently tie the canes together to help protect them against breakage. The canes are brittle in the winter and even the slightest wind can knock them over.
If you live in a warmer area, the canes should be cut to about 4 feet, but they do not have to be tied.
Mulch the rose bushes (no matter what climate you live in) in the fall. Make sure the graft union at the bottom of the plant is covered with at least 3 inches of pulverized bark or compost. The graft union is especially susceptible to the cold.
Mulching and Watering
Keep plants mulched during the spring, summer and fall, but make sure the graft union is exposed, so the plant can breathe properly. Rose bushes should be watered as instructed by the nursery, but in the absence of instruction, most rose bushes need at least 1 inch of water every week.
Numerous fungi affect rose bushes. The most common fungi are various cankers (brand canker, crown canker), anthracnose, botrytis, black mildew, leaf scorch, rose ruse, wilt and powdery mildew. Most of these can be controlled with fungicide, but if they are not caught, the only way to control the fungi is to remove and destroy the plants before they spread to healthy plants.
Several pests are attracted to roses, but the most common are cane borers, aphids, gall wasps, bees, leaf cutters, slugs, scale insects, weevils and thrips.
Most pests can be controlled with pesticide, but if you are having a particularly bad year for pests, put screening (made especially for plants) over the roses. Some pests must be picked off by hand -- they show up at certain times of the day. For example, the chafer beetle shows up for four to six weeks in the summer. Remove these by going out when they are their quietest (early morning or late evening) to pick them off the flowers. Chafer beetles do not kill the plant, but they can do enough damage to the plant to make it unhealthy.