When looking over a shrub before pruning, there are certain definite classes of material that must be considered for removal.
Dead or diseased wood or wood that is seriously infested with insects.
Weak wood that is not productive of bloom.
Excess suckers and shoots, whether originating from the base or on the upper part of the trunks.
Branches that are rubbing.
Keep in mind your purpose in pruning. Are you pruning to keep growth in scale with the surroundings, maximum flowering and/or fruiting, enhance form, etc.? Prune for a purpose, not just because the shears and saw are handy.
Time and Frequency of Pruning
Prune the following shrubs during the dormant season. All are summer-flowering plants that produce their blooms on growth of the same season.
Abelia grandiflora
Aesculus parviflora (bottlebrush buckeye)
Amorpha (leadplant)
*Buddleia (butterfly bush), except B. alternifolia
Callicarpa (beautyberry)
*Caryoptris (blue spirea)
Ceanothus (New Jersey tea or redroot)
Clethra (summersweet, sweet pepperbush)
*Cornus (dogwood species w/brightly colored stems)
Diervilla (dwarf bush-honeysuckle)
Hibiscus syriacus (Rose of Sharon)
Hydrangea (florists varieties)
*Hydrangea arborescens ‘Grandiflora’ (Hills of Snow)
*Hydrangea paniculata ‘Grandiflora’ (Pee Gee)
Hypericum (St. Johnswort)
Lespedeza (bush clover)
Ligustrum (privet)
Pontentilla (cinquefoil)
Rosa (hybrid tea)
*Sorbaria (false spirea)
Spiraea bumalda ‘Anthony Waterer’
Spiraea billardii
*Symphoricarpus (snowberry)
*Tamarix
*Vitex (chaste tree)
*Generally requires annual maintenance pruning in February or March. May also be cut back severely, if necessary, at that time.
The spring-flowering shrubs should be selectively maintenance pruned in late winter/early spring before foliage appears or immediately after flowering. Thin old, unproductive canes/branches every 1 to 2 years by cutting out at ground level. Head back out-of-scale upper and outward-spreading branches to a lateral. If pruning early in the season, be aware that some flowering will be sacrificed, but branch structure and habit will be more obvious with the plant void of foliage. By following this more frequent schedule of maintenance pruning, plants will remain in scale and rarely require major rejuvenation.
Deutzia
Exochorda (pearlbush)
Forsythia (shrub types)
Jasminum nudiflorum (winter jasmine)
Kerria japonica (Japanese kerria)
Kolkwitzia amabilis (beautybush)
Physocarpus opulifolius (ninebark)
Philadelphus (mock orange)
Pyracantha coccinea
Stephanandra incisa (cutleaf stephanandra)
Spiraea arguta (garland spirea)
Spiraea prunifolia (bridal wreath)
Spiraea thunbergii (thunberg spirea)
Spiraea x vanhouttei (Vanhoutte spirea)
Weigela florida (old fashioned weigela)