Early spring pruning

In early spring prune summer-flowering trees and shrubs that bloom on new growth, non-blooming broadleaved evergreen plants, and evergreen or deciduous hedges. Also prune hybrid tea, floribunda, grandiflora, and miniature roses. Cut away winter killed growth from climbing and rambling roses. 

Pruning just before new growth begins allows for faster healing and stimulates growth.

In late spring or early summer prune spring flowering shrubs immediately after blooms fade. This is the time to prune your azaleas and rhododendrons as they will soon set buds for next year's flowers. Do not prune more than one-third of the plant each year.  If you need to do heavy pruning, space it over two or three years.  Trim half of new candles on pines and other needled evergreens.

In summer shear or shape evergreen hedges. Pruning in the summer when plants are actively growing can actually harm plants by exposing previously shaded tissue to the sun possibly causing scorching. It may also dwarf a plant because it uses all its energy to close wounds left by pruning. Summer pruning can subdue growth making fast growing hedges easier to control. Hot weather pruning also minimizes the formation of suckers.

Prune climbing roses which are more than 2 or 3 years old and rambling roses after they bloom. If needed prune maples, dogwoods, walnuts, and yellowwoods. Summer flowering shrubs and trees should be pruned as blossoms fade.

In fall trim long rose canes as the harsh winter winds will harm them and surrounding objects as the wind thrashes them around.

This is the worst time to shear plants because it encourages new growth that may not have time to harden before the winter, the new growth will possibly be killed by the cold.  It is, however, okay to thin plants in the fall after plants are dormant.

In winter prune berried shrubs and trees by harvesting them for holiday decor.  Prune deciduous plants and fruit trees that do not flower in late winter or spring making sure that the temperature is above 20 degrees F.

Pruning deciduous plants when most plants are dormant promotes regrowth in spring.  It is easier to prune this time of year because you can see the shape of the tree without the foliage in the way.
Schedule pruning for the end of winter, wound closure begins in spring.

Beware of over pruning.  Many plants do not tolerate heavy pruning. The general rule is to remove no more than 1/4 of the plant at one time and not more than 1/3 during the year.