Don't turn your back on these plants, though, because pruning may be needed now to encourage repeat performances next year and in years to come.
Many shrubs and vines renew themselves by each year sending up new stems at or near ground level. With age, older stems may begin to crowd each other, flower less profusely, and put fragrant or colorful blossoms beyond where you can best appreciate them.
OUT WITH THE OLD, IN WITH THE NEW
Cutting away some old stems makes way for new ones. Pruning also keeps plants shapely, and gets rid of diseased, dead or broken branches.
Pruning spring-flowering shrubs and vines right after flowers fade gives new shoots time to grow and bud up this year for flowers next year.
Vines need enough pruning to keep them in bounds, which varies from plant to plant. Dutchman's pipes (Aristolochia spp.), for example, needs nothing more that a light going-over with hand shears because it flowers well on old stems. At the other extreme is Crimson Star clematis, which flowers on 1-year-old stems, so puts on its best show if lopped almost to ground level each year right after flowers fade. New stems will grow, on which next years blossoms will open.
Spring-flowering shrubs, too, vary in the amount of annual pruning they require. Those that tend to send up few new suckers (sprouts growing at or near ground level) — pagoda dogwood and cotoneaster, for example — require little or no annual pruning.
SO LONG, SUCKERS
If you're not sure how much to prune a shrub, watch it grow for a year; the more suckers, the more pruning needed.
Lilac and forsythia are among those spring-flowering shrubs that sucker profusely. Prune them with a pair of loppers (or a pruning saw, if stems are too thick for the loppers) and a pair of pruning shears, using the tools in that order as you move progressively from grosser to finer cuts.
Begin by peering in at the base of the shrub so you can find and cut away some of the very oldest stems to within a foot or less of the ground. Those stems are the tallest, so these first cuts also keep these shrubs from growing too tall.
Selectively cut wood from any shrubs that are beginning to send up new suckers further and further away from the original base of the plant. Next, with your loppers, lower some of the remaining older stems. Strive for a fountain effect, cutting back to a vigorous side branch any stem that is too tall or too droopy.
Finally, with pruning shears in hand, go to work on the suckers. Thin them out where they grow too densely so that those that remain have sufficient elbow room as they grow older.
Stop work for a minute, now, and look at what's lying on the ground. Branches, yes. But just as important: spent flowers at the ends of all those branches. Those spent flowers would have developed seeds. Now all that energy that would have gone into developing seeds can be channeled into flowers for next year.
MAKE IT PRETTY
Wrap up your pruning job with detail work, using pruning shears. Clip off any remaining spent flowers. Cut away any small branches that droop too much or gawkily jut out the top of the "fountain." It is impossible to give an exact prescription for what to cut. Such details depend on the nature of the plant, as well as how high and how wide you want it to grow.
There is art in pruning, and as you prune, step back periodically — as any artist would do — to evaluate and admire your work.
More detailed instructions for specific shrubs are offered in "The Pruning Book," by Lee Reich (Taunton Press, 2010).