pruning roundup: what shrubs i prune when

WHAT NOT TO DO IS AS IMPORTANT many times as what to do each season, the dont’s as powerful as the do’s. Nowhere is this more to the point than with pruning, the “there’s no turning around now” portion of horticulture, where you can’t glue it back on or wait a few weeks for another (forgiving) flush of foliage, as when you give a ratty perennial or annual a needed haircut. Are you feeling scissor-happy? Read this first.

Each May and June I’m asked, “Why didn’t my lilacs bloom?” only to find out in the next sentence that the questioners had literally nipped the plants in the (flower) bud with late summer, fall, winter or earliest springtime pruning, long after the new year’s blossoms had been set.

Early bloomers flower on old wood. Go out and look at a forsythia or a lilac: Unless you pruned in summer or fall, you’ll see flower buds already in place, dormant but there. If you prune now, it won’t flower now. Make sense?

Generally speaking, don’t prune spring-blooming shrubs and trees more than a month or so after they finish blooming. After flowering, prune immediately. You will typically not harm the plant by pruning a little later, but you will be deprived a season of bloom, so why not first enjoy it?

Woody plants that flower late in the season, such as Hydrangea paniculata, bloom on new wood. Again, go out and look. You don’t see any flower buds now, in early spring, do you? Bottom line:

Discovering where on the stems and when the plant creates its flower buds will help direct your pruning efforts.

details, details:

LILAC pruning: Unless the shrub’s a neglected wreck in need of rejuvenation, cutting off bouquets of flowers is all the pruning you’ll want to do. I never prune them here in my Zone 5B climate after July 4, except

prune pruning how-to trees & shrubs for beginners