Pruning: What is it and Why do it? - Terrascapes

Pruning involves the selective removal of specific parts of a plant for the benefit of the whole plant. Pruning can dwarf a plant, make it grow taller, open the canopy or make it denser. Pruning should be viewed as routine maintenance of the tree rather than a remedial correction of long neglected problems. (Info taken from Cornell University Coop Extension)

General Tips for Pruning

Remedial pruning to remove dead, broken, or diseased branches can be done at any time of year with little negative effect on the plant.

Just before bud break

Bud break

Leaves fully expanded

New shoots reach full growth and start to become woody

Prune roses & summer blooming shrubs: hydrangea, rose of Sharon, glossy abelia, Buddleia (butterfly bush), Caryopteris (bluebeard), Cornus (dogwood species with brightly colored bark), Hypericum (St.-John’s-wort), Perovskia (Russian sage), privet, Potentilla (cinquefoil), Sorbaria (false spirea), Spiraea bumalda, S. billiardii, and Symphoricarpos (snowberry).

Head back growth of random branched conifer species: junipers, Chamaecyparis (false cypress), yews, and arborvitae.

Train young shade trees planted the previous year by selecting scaffold branches, removing others.

Preferred time to rejuvenate evergreen and deciduous shrubs and hedes that are out of bounds

Best time to annually prune most vines.

Alternate time to thin mature trees.

Avoid pruning species prone to bleeding (birch, elm, maple, yellowwood).

Best not to prune any woody plants at this time due to translocation of carbohydrates and growth hormones to growing points.

Rub off trunk buds that will give rise to suckers and water sprouts.

Prune spring –flowering shrubs soon after blooming period: azaleas, Deutzia, pearlbush, Forsythia, Kerria, Kolkwitzia (beauty bush), ninebark, Philadelphus (mock orange), Rhododendron, Spiraea prunifolia (bridal-wreath spirea), S. thunbergii, S. vanhouttei, and Weigela.

For more compact growth, pinch out ½ of the new growth of pines, spruces, and firs.

Clip back the terminals of vigorous new shoots as well as spent flowers in ericaceous species (Rhododendron, azaleas, mountain laurel, Andromeda); this will keep plants compact and encourage production of side shoots and flower buds.

Evergreen shrubs or hedges that were pruned heavily in late winter or early spring can be trimmed now to re-establish clean lines.

Prefereed time to perform major thinning operations on crab apples, callery pears, ornamental cherries and plums, honey locust, maples, spruces, willows, and poplars to reduce susceptibility to trunk cankers.

Rework the interiors of tree-form dogwoods to remove overly shaded, crisscrossed, or weak branches.

Alternate time to rejuvenate hedges.

New shoots fully mature; early stages of fall color

Full coloration of leaves: some leaf fall

After several hard frosts

After hard freezes; plants truly dormant

Heavy pruning at this time can result in stimulation of new shoots that may not properly harden before winter; limit pruning to the removal of damaged or dead wood, especially on conifers.

Wisteria may be pruned at this time.

Clip away excess ivy growth on building walls and around windows: English ivy, Boston ivy, and Virginia creeper.

Alternate time to perform major pruning of onocanker-prone species

Thin crown of mature trees; remove dead or storm-damaged limbs

Clip hedges to retain clean lines

In late winter rejuvenate shrubs that are out of bounds.