Dr. Gouin's Bay Gardener

Pruning Roses

Roses need to be pruned yearly to keep the plants strong and healthy. Spring-flowering roses should only be pruned after they have flowered, while summer flowering roses should be pruned in mid to late March.

Hybrid T and floribunda roses that have been in the ground for five years or less should be pruned to within 12 inches of the graft union. The cut end of all pruned stems that are pencil-width in diameter or larger should be treated with paint, nail polish or carpenters glue to prevent cane borers from entering. Even a thumbtack stuck into the cut end of the stem will prevent cane borers from becoming established.

Make certain when pruning to remove all canes that are infested with cane borers. Cane borers make perfectly round holes; their progress can be followed by pruning until you uncover solid wood. If the cane borer has entered the graft union, which is that knob that separates the stems from the roots, it is often too late to prevent the death of the graft union.

As Hybrid T’s and floribunda roses grow older, the stems are not pruned as severely. The stems of older roses are generally pruned to within 18 to 24 inches of the graft union. However, all side branches, or suckers, less than a pencil-width in diameter are removed, and all remaining branches are pruned, leaving at least two buds on each branch.

Mounding roses and old-fashioned roses are grown on their own roots and thus can be pruned to the ground without loss of variety. Mounding roses are becoming very popular because they are generally disease and insect free and flower all summer long. I even prune mine with the lawn mower.

Professor Emeritus Francis Gouin retired from the University of Maryland, where he was the state’s extension specialist in ornamental horticulture. Follow his column of practical gardening and plant advice every week, only in Bay Weekly. Ask Dr. Gouin your questions at [email protected].