Pruning shrubs and trees is one of the regular gardening tasks that should be carried out every year. As with all jobs there is a right way and a wrong way to complete them so here is some useful advice from the experts at Penn State Extension. I came across this article on their website.
With spring on the doorstep, now is an excellent time to prune some of your shrubs and trees. Pruning manages the size and shape of a tree or shrub, and is used to remove dead, damaged and diseased branches, suckers and crossing branches that rub together.
In addition to improving a plant?s appearance, correct pruning promotes plant health and encourages flower and fruit development. Additionally, pruning hazardous trees protects you and your property. Here are some tips to follow when pruning specific plants, the best tools to use and some basic techniques.
Late winter, while plants are still dormant, is the ideal time for pruning many trees and shrubs. Pruning wounds are exposed for a short time before new growth and healing begins and you can see the structure of a deciduous plant before leaves obscure it. Prune apple trees (Malus pumila), flowering crabapples (Malus spp.) and cotoneasters (Cotoneaster spp.) now to reduce the chance of the bacterial disease, fireblight. Also prune maple (Acer spp.), birch (Betula spp.) and walnut (Juglans spp.) trees at this time as they have free flowing sap that ?bleeds? when they are no longer dormant. It is important to prune oak, especially trees in the red oak group, while they are dormant to prevent insects from entering pruning wounds and transmitting oak wilt.
Prune summer and fall flowering shrubs in early spring before buds break and the plants leaf out. These are shrubs that ?bloom on new wood,? or the current season?s growth. They include sweetshrub (Calycanthus floridus), beautyberry (Callicarpa spp.), summersweet (Clethra spp.), bush honeysuckle (Diervilla spp.), smooth hydrangea (Hydrangea arborescens), PeeGee hydrangea (Hydrangea paniculata), summer-blooming spirea (Spiraea x bumalda and S. japonica) and repeat-blooming roses (Rosa spp. and hybrids.)
See more at Penn State Extension