Pruning Broad-Leaved Evergreens
Broad-leaved evergreens require very little pruning. You will want to lightly thin broad-leaved evergreens during the dormant season if needed for shaping. Remove old or weak stems. This group can go several years without pruning except for some slight cosmetic pruning to keep them neat. Try not to remove too much wood from these plants; if too much is removed at any time during the summer or winter, the amount of fruit is reduced the following season.
When these plants become old and straggly, cut them back 6 to 8 inches from the ground before spring growth begins. Don't cut them back too early, however, because a flush of growth could freeze and set them back. Prune only after the danger of the last killing frost is past. Such pruning stimulates the growth of new shoots from the base of the plant.
Many gardeners prefer to remove only about one-third of the branches at one time and retain the general contour of the plant. This method also can be used. In the long run, probably the best thing to do with overgrown broad-leaved evergreens is to remove and replace them.
Pruning Narrow-Leaved Evergreens
Since narrow-leaved evergreens produce new growth in spring and fall and do not grow much in summer, prune the first or second week of May or June in Portland. The only exception to this rule is pines, which should be pruned before the candle growth develops in the spring.
Prune evergreens according to their growth habits. Allow these plants to assume their natural shape. Pruning is a matter of cutting the branches so that a more desirable plant is attained through compact, controlled growth. By pruning individual stems rather than shearing, shearing not only ruins the natural growth habit but prevents light from penetrating into the center of the plant resulting in foliage drop.