SHRUBS AND VINES PRUNING TIPS
Flowering shrubs are planted for their colorful bloom and usually require little pruning. Winter injury or long neglect may require a major thinning out. It is best to prune the oldest and poorest branches back to the ground and shorten the others to reasonable lengths to keep the plant from becoming leggy or straggly. They are most beautiful when allowed to take their natural forms.
Some shrubs like lilac and honeysuckle benefit from occasional drastic pruning. Lilacs should be pruned after flowering. Unless kept in control they have the tendency to grow too tall and become leggy. The oldest, thickest branches on an uncared for lilac should be cut nearly to the ground to start an entirely new plant.
When to Prune Flowering Shrubs - depends on whether it flowers on branches that are produced in the current season or on branches that grew during the previous year. If you do not know for sure there is no fool proof way to tell by looking if a plant blooms on old or new wood. Often plants that bloom early have flowers on last year’s branches and those that flower later, bloom on new branches. Look for additional information on the specific shrub variety.
Old-Branch Flowering Shrubs - should be pruned right after the flowers fade. Do not prune in winter or spring, you will cut away flower buds. Prune immediately after they flower, so they have time to develop a new set of buds to flower the following spring. Examples are beautybush, aternifolia, forsythia, honeysuckle, lilac, magnolia and azaleas.
After old-branch flowering shrubs have borne flowers, cut back those old shoots leaving vigorous young shoots lower down on the main stems. Remove new shoots only if they spoil the shape of the plant. On shrubs three or more years old, begin to remove some of the oldest branches at the base of the plant leaving room for new shoots to become major branches.
New-Branch Flowering Shrubs - may be pruned when dormant in late winter or early spring before the buds become green. Some examples are Crape Myrtle, Spreading Euonymus, Hibiscus Syriacus, Hydrangea Paniculata, Potentilla, Witch Hazel and some spireas like S. Japonica.
Shrubs that flower on new branches should be left alone to form strong central branches in their first several years. After a couple of years, annually prune back new shoots to the last one or two buds of last year’s growth. This encourages a fuller, thicker bush as it matures. Eventually, you may want to remove some older branches at their base to encourage continued new growth.
Vines - Since the purpose of woody vines is usually to drape or screen objects, it is desirable to prune them only to induce new growth at the base. Dead wood should be cut out at any time and precocious shoots should be kept within bounds. Other than this, the less shears are used, the better.
Most flowering vines bloom on wood formed the previous year, so try to do any minor pruning after flowering. However, if you plan drastic pruning, wait until the vines are dormant to prune.