Landscape - Pruning

Late winter is a good time to prune some ornamental plants. The following are some guidelines on pruning.

Pruning Ornamental Plants

Reasons for Pruning

• To keep plants at desired size.
• To remove all dead, diseased, broken and injured parts.
• To develop certain forms or shapes--formal, informal, espalier, etc.
• To encourage best growth for flowers and fruits.
• To rejuvenate declining plants.

Basic Pruning Equipment

• Hand pruners - There are a number of styles but get a good pair. Cheap shears are a poor value.
• Loppers - Long-handle loppers will handle stems up to 1 - 1½" in diameter.
• Pruning Saw - Small saws with fine teeth are best for shrubs and small limbs. Larger saws with coarse teeth are needed for large tree limbs.
• Hedge Shears - If hedges or other evergreens are to be sheared, power hedge shears or hand hedge shears are needed.

When to Prune

Evergreen Plants: Most evergreens may be pruned in winter and early spring. Needle-type evergreens are often pruned twice: heavy cuts in early spring and a light tipping back of one-third to one-half the immature, soft, new growth in June. Avoid pruning evergreens in the summer and early fall.

Broadleaf Evergreens: Prune broadleaf evergreens just before growth starts in the spring or immediately after flowering for those that formed flower buds the previous year. Cut back hedges in early summer or as soon as the new growth is complete.

Trees: Trees can be pruned at any time of year. It is easiest when branches are bare in late winter. Trees that bleed can be pruned in early summer or fall. However, bleeding causes little permanent harm to the tree.

Early-Flowering Shrubs: Those that bloom in March, April, May and early June -- are pruned immediately after flowering.

Late-Flowering Shrubs: Those that bloom in late June, July and August -- are pruned in late winter or early spring (late February, March or early April).

Pruning Cuts

In pruning, it is important to make cuts in relation to live buds that will grow to produce new branches and to eliminate any stubs that will fail to heal over and result in places of entry for insects and diseases.

How to Prune Some Popular Ornamental Plants

Arborvitae: Shape in late winter. Prune to forks with foliage remaining on all branches. Shear back new growth the end of June if needed.
Azalea: Prune after flowering if needed. Cut back leggy stems to shape plant. Prune to forks.
Barberry (deciduous): In late winter cut old wood back to the ground, shape the remaining branches.
Birches: In early summer remove branches that form weak narrow crotches and branches that cover the main trunks so that bark pattern is enhanced.
Butterfly Bush: In late winter remove all old wood and cut back last year's growth to a few buds. Boxwood: Cut out diseased or injured wood in late winter. Shear new growth the end of June.
Crabapple: In late winter prune to shape. Remove suckers and thin out competing branches.
Crepe Myrtle: In late winter cut out all thin weak wood and head back remaining branches.
Dogwood: In late winter prune to shape. Cut out sharp angled branches. Be sure all cuts are smooth and painted with tree paint.
Forsythia: After flowering remove all four-year-old wood to the ground. Try to keep a natural arching form.
Hemlock: Shape in late winter. Shear again in midsummer if needed.
Juniper: In late winter prune to improve shape. Cut tips of branches back to a fork. Can be repeated in late June if needed.
Magnolia: In winter remove suckers. After flowering, prune only very lightly to improve form. Do not leave any stubs.
Maple: In summer or fall prune to shape.
Oak: In winter prune to shape.
Pine: In winter prune to shape. Cut only to forks and do not leave any stubs. To increase density, cut back candles (new growth) just as needles form.
Taxus or Yew: Shape in late winter. Cut back new growth in late June if needed.
Wisteria: In winter cut out excess branches and establish framework. Cut all remaining branches back to 2 or 3 buds. Cut back vigorous growth several times during the summer.

Reprinted from the factsheet "Pruning Ornamental Plants" by Jay Windsor, Agricultural Agent, University of Delaware Cooperative Extension.