Sharpen those shears and get ready to prune.
Roses are pruned just before growth begins in early April. The exceptions are heirloom roses and some climbers that produce blooms on the previous year's wood. These are pruned after they bloom.
There are several steps to pruning hybrid teas, grandifloras, and floribundas.
Start by removing any dead, diseased or damaged canes. Cut an inch below darkened areas on canes, making sure you are cutting back to green wood. Make cuts at a 45-degree angle about one-quarter inch above an outward-facing bud. The pith in the center of the stem should be white; if it's tan-colored, continue pruning back until the pith is white.
Next, remove branches that grow inward, toward the center of the plant. This opens the plant for better air circulation and allows sunlight to penetrate.
Now locate crossing branches and remove the weakest one. Crossing branches can rub against one another and cause abrasions that serve as openings for diseases.
Remove all sucker growth, which comes from below the bud union. This growth is from the rootstock and is a different rose variety; if not removed, sucker growth will crowd out the desired variety.
Finally, prune to shape the plant by cutting canes to 12 to 24 inches tall, leaving about nine to 12 large (half-inch diameter) and healthy canes.
Old roses, newer shrub roses and species roses should be pruned sparingly, removing no more than a third of the plant.
Use thinning cuts to remove branches growing inward and crossing branches. Make heading cuts as needed to encourage branching where needed. Miniature roses need only minimal pruning.
Hydrangeas have been popular in recent years, but gardeners are still confused about how to prune them. The key to pruning is knowing which plant you have and when it flowers.
If you have oak-leaf hydrangea (Hydrangea quercifolia) or bigleaf hydrangea (H. macrophylla), which includes the lacecaps and mopheads, prune them after they flower in the spring.
The flower buds on these two species are set in late summer and spend the winter on the plant. Note that flower buds on the bigleaf hydrangea are not fully hardy in our zone, and if winters are cold and harsh, they might not survive to open in the spring.
Smooth hydrangea (H. arborescens) or panicled hydrangea (H. paniculata) can be pruned now. Both of these species flower on new wood; their buds are set on new growth this year.
Clematis is the last group of plants for pruning for this week. The early flowering clematis generally bloom in April and May from buds produced the previous season.
Prune these plants immediately after flowering, but no later than the end of July. This allows time for new growth to produce flower buds for the next season.
Remove the shoots that have bloomed. You can also prune out more vines to reduce the size or form a good framework of branches, but avoid cutting into woody trunks.
Plants in this group include Clematis alpina, C. macropetala, C. armandii, C. montana and C. chrysocoma.
Large-flowered hybrid clematises bloom in mid-June on short stems from the previous season's growth and often again in late summer on new growth, although these blooms are usually smaller.
Prune in March by removing dead and weak stems, then cut back the remaining stems to the topmost pair of large, plump green buds. This cut could be 6 to 18 inches from the stem tips. These clematis have the tendency to become leafless at the base as they mature.
You might be able to force a flush growth from the base by cutting the vine back to 18 inches immediately after the flush of bloom in June.
Plants in this group include varieties such as Nelly Moser, Miss Bateman, Duchess of Edinburgh and Mrs. Cholmondeley.
The late-flowering sweet autumn clematis blooms on new growth, so cut this plant back now to about 18 inches tall, just above a pair of buds.
I'll write more next week on pruning and rejuvenating shrubs in the landscape.
Article by JANE C. MARTIN
Jane C. Martin is a horticulturist. Gardeners may find answers to their questions at plantfacts.osu.edu/faq.
