Now that most spring flowering shrubs have finished blooming, it’s OK to prune them. An arborist’s best practice, however, is to prune only to meet specific objectives, not just because they’ve finished blooming.
Objectives may include reducing the height or girth or removing interfering shoots. Shoots may be cascading over a sidewalk or driveway. This doesn’t mean that you should cut back the whole shrub. Just remove the offending shoots.
Don’t prune spring flowering shrubs back to the ground like you do with later blooming shrubs like butterfly bushes (Buddleia davidii). These plants bloom on new wood. Early blooming shrubs like forsythia and lilacs bloom on last year’s wood. If you prune that wood as far back as you would a butterfly bush, you could kill the shrub since you’ve removed most or all of the leaf buds, as well.
Early blooming shrubs set their flower buds in the fall. If you prune before they bloom, there’s a good chance you’ll cut off these flower buds. This could result in a spring with no flowers on the pruned shrub.
When pruning early spring bloomers, use good, sharp, bypass pruners. These work like scissors; the blades cut cleanly as they bypass each other. The other style pruning shears are anvil style. As you apply pressure, a sharp blade on one half goes into a shallow groove on the other half. As the blade dulls, the cuts become more ragged. For pruning in hard to reach places, use loppers. (Loppers are always bypass style.)
Ideally, you should make your shrub pruning cuts at ground level and remove whole shoots. If you are just reducing the height rather than thinning, make your cuts at branch joints if possible. Absent any joints, cut just above a leaf.
It’s not a good idea to use hedge clippers on woody shrubs. The wood is usually too dense to make a clean cut with hedge clippers. Wood can also jam in the teeth of electric clippers and removing the wood can be dangerous.
Wear a long sleeve shirt and gloves when pruning shrubs. When you reach inside a shrub, the surrounding branches can be very sharp.
DIY shrub pruning is not as dangerous as pruning trees but it isn’t accident-free. Our arborists have the training, experience and equipment to prune shrubs safely, and they would be happy to do the job for you.
I just addressed this in one of my ‘rant’ articles recently. Most shrubbery gets shorn over and over and over and over and over . . . .