Planning Your Garden Pruning

Deciduous Trees & Shrubs
Many deciduous trees and shrubs are planted in the home landscape for their attractive flowers. So, begin by deciding whether the plant has attractive flowers and when during the growing season those flowers appear.

Spring flowering trees and shrubs – like azalea, crabapple, dogwood, lilac, forsythia, magnolia, redbud, rhododendron, serviceberry, viburnum, weigelia - bloom early on the previous season’s growth. If only light maintenance pruning is needed, then prune immediately after bloom. Pruning at this time allows gardeners to enjoy the spring flower display and gives adequate time to initiate flower buds for next season. Maintenance pruning includes light shaping; removal of suckers or watersprouts; or removal of rubbing branches. 

Some trees, such as maples and birches, bleed sap heavily when pruned in late winter or early spring. The heavy sap leakage, however, doesn't harm the trees. The flow of sap will gradually slow and stop.

Non-blooming deciduous shrubs – Some shrubs don't produce showy attractive flowers, like burning bush and privet. Instead, they are grown for their attractive bark, fruit, or fall leaf color. Often these plants are used for hedges. Ideally, heavy pruning is done in late winter or early spring before growth begins, but they can be pruned in mid-summer, too. However, avoid pruning hedges during very hot, dry weather which often occurs in July and August.

Don't prune deciduous shrubs in late summer. Late August or early September pruning may encourage a late flush of growth, which often does not have enough time to harden off sufficiently before the arrival of cold weather making it susceptible to cold temperature injury.

Oaks – To minimize the potential for oak wilt infections, avoid pruning from April through June. Ideally trees should be prune from early to late March.

Old, neglected shrubs – Heavily overgrown shrubs often require extensive pruning to rejuvenate or renew the plants. The best time to rejuvenate large, overgrown shrubs is late winter or early spring (March or early April). While heavy pruning at this time will reduce or eliminate the flower display for a few years, the long-term health of the shrubs is more important.

Grapes
Prune grapevines from late February through early April. Vines will often bleed sap heavily from the pruning wounds. The sap loss, however, is not a problem for plant health.

Everbearing raspberries managed for one large crop – prune all canes in fall or late winter (early to mid-March) while the ground is frozen and before new growth has begun. Using hand pruners, rotary mower, or other mechanical device, remove all above ground growth leaving a 1- to 2-inch stub for each cane. In August or early September, fruiting will occur on the current season's growth.