Plan to prune in the winter before the buds begin to swell, using clean, sharpened tools so your cuts promote the health of the plants. Use pruning shears for cuts of half an inch or less in diameter, loppers for cuts up to 1 inch in diameter and pruning saws for anything larger. If you are pruning out diseased wood, dip your tools in a 10 percent bleach solution to avoid spreading disease, and then oil your tools when you are finished to prevent rust on the blades.
Hybrid, tea, floribunda and grandiflora roses benefit from yearly pruning. Landscape varieties can be pruned biannually to remove older canes and rejuvenate the plant and be either hedged or left unpruned on the off year.
Begin by removing any leaves or old flowers on the plant, as well as all leaves on the ground around each rose. Prune out the dead or diseased canes and then remove any crossing canes or canes growing toward the middle of the plant. You’ll want to end up with three to five main canes in a vase-like formation after you’ve finished pruning.
Ideal pruning cuts should be made about one-quarter inch above a healthy, outward-facing bud. The cut should be angled at 45 degrees, with the lower end of the cut just opposite the bud, so that water is shed away from the bud rather than onto it. Keep the thin blade of your pruners, the cutting blade, nearer the bud to which you are cutting; otherwise, you might crush the stem, leaving a jagged injury that is open to infection.
During the growing season, removal of spent blossoms allows the rose to conserve energy and leads to further flower production. Cut blooms on first-year plants to just above the first outward-facing, five-leaflet group. On well-established plants, cut the blooms lower to ensure that new canes can support the weight of the blooms.
• The Green Thumb is a column by Tracy’s master gardeners. University of California-certified master gardeners are available to answer gardening questions from 9 a.m. to noon Tuesdays, Wednesdays and Thursdays at 953-6112 or firstname.lastname@example.org.