Follow these suggestions in order to reduce the potential for disease as well as to encourage vigorous new growth:
1. Thoroughly clean the rose beds of dead leaves and other debris. You will reduce the potential for various insects and fungi to survive the winter by eliminating the places in which they hide. Bag all pruned material from the bushes. Don't use rose stems for mulch or compost; many fungal spores can invade the stems and cause reinfections when the warmer weather returns.
2. To ensure the destruction of all insects and fungi, apply a dormant pesticide or fungicide spray immediately after pruning -- when there are no eyes developing. Use the old-fashioned oil-and-sulfur spray to help destroy both powdery and downy mildew spores residing in the soil and on the canes. Inorganic sulfur compounds are available at garden centers. Follow instructions on the label to mix with horticultural oil.
3. After brushing the bud union with a wire brush to remove the old bark, cover the bud union with about 6 to 10 inches of the surrounding mulch. This protective mound of mulch keeps the bud union moist and receptive to new canes. Additionally, this mound can protect the bud union from mild frost and wind chill. Many rose experts avoid this step, believing it promotes a plant disease known as crown gall.
4. Avoid fertilization until about three or four weeks after pruning. Then apply 1 to 2 cups of a balanced granular rose food around the base of the mound covering the bud union, and then uncover the bud union. The mulch then provides a clean landscaping surface to start off the new year.
Continued on page 3: Pruning in a Winter Climate