Pruning improves appearance, stimulates growth, aids in disease management, and controls the quality and quantity of bloom. Pruning removes the parts of the plant that are unproductive, dead, damaged, or diseased.
Plants are always improved and never killed by pruning. Incorrect pruning is better than no pruning at all. Unpruned rose plants will produce some early inferior blooms on short stems. Production will cease after the first bloom and repeat bloom will most likely not occur.
Light pruning of most hybrid teas results in tall, spindly plants, which produce smaller blooms. Moderate t o hard pruning is preferable and produces fewer, but larger blooms. Moderate pruning removes 1/2 to 2/3 of the plant; hard pruning leaves only 3-4 canes, 8-12″ long. Prune strong plants moderately and weak growers severely. Roses, which bloom on last year’s growth, however, such as climbers, and many Old Garden Roses, should be lightly pruned or thinned only, removing old, unproductive canes.
Generally, February 22 until mid-March is the optimum pruning time in the Greater Seattle area. Nature’s indicator is when the Forsythia is blooming in your neighborhood. It is sensitive to light and temperature and blooms at the optimal time.
Use scissor-type, bypass shears when pruning. A keyhole saw with fine teeth will reduce tearing of the bark in tight areas, or on large canes. Anvil type shears will crush or bruise canes, leading to infection.
Cut approximately 1/4″ above a bud eye. Cutting closer will injure or kill the bud and cutting farther away will leave a section of dead cane to attract insects and disease spores.
With modern roses, the pith color at the pruning cut should be a greenish white. Any brown coloration in the pith indicates a dead or dying cane; the cane should be pruned to a lower bud eye, clear to the crown, if necessary, in order to find live pith. Healthy looking canes should be pruned first, so that if the pith is dark and the canes must be removed, the smaller, older, or crossing canes will still be available.
Pruning to an outside bud will force growth outward, opening the center of the plant to sunlight and air circulation. Pruning to an inside eye on sprawling varieties or those in a restricted space will force growth inward and keep them in check.