Normally we begin pruning trees and shrubs in late November or early December, just after the first frost. But in hot and dry summers, your landscape may have experienced more mortality than in previous years and you may want to begin pruning earlier this year.
Always begin with a plan. Start with plants that have dead branches. Look at the buds and the bark. Dead branches will not have any full buds at the tips or will have loose or sunken bark. If these are not readily apparent, scratch the bark with your fingernail or pocket knife. A living branch will be green beneath the bark. A dead one will not.
Next, remove twigs and branches that may be diseased or infested with insects. Diseased branches will be discolored or have sunken bark. Twigs and branches infested with insects will have pitted or discolored bark – or the eggs or body parts will still be evident.
It's always important to remove the entire dead or infested branch. Prune it back to a main trunk, or major branch of equal or larger size. Of course, topping – or removing all the branches until you are left with several big stubs – is always discouraged for both trees and shrubs.
Finally, for shrubs and perennials, a very light reduction of the green top foliage and thinning of the interior branches will maintain the balance of shoots to roots. And, this will induce vigorous new growth next spring to help produce new roots. Prune no more than 20 percent of the entire green plant.