"I brake for butchered plants."
Perhaps that's what my bumper sticker should read, because I did almost slam on my brakes recently to try and save a forsythia bush - a whole row of them, in fact - from being butchered. An obviously well-intentioned homeowner was attacking the bushes on his front lawn with loppers.
A few things were wrong with this scene.
Lopping in the wrong place.
While loppers are, in fact, the main tool in pruning forsythia, this guy, unfortunately, was standing upright and using them at chest height. Lopping all branches to this height creates a bush that rises up like a graceful fountain, then loses that grace in a wild burst of chest-high growth.
As with shortening a stem on any plant, from a mum to an apple to an indoor avocado, buds just behind the cut are awakened to grow out into shoots.
Some people use hedge shears on forsythia, with equally ungraceful results. All that a hedge shears does is coax lots of new growth right where all those cuts are made.
Why not let a forsythia bush be the graceful fountain of growth that it's trying to be? It does need pruning, of course, to rid it periodically of decrepit old stems and make way for young, flowering ones. But the way to prune and maintain that graceful, arching form is by using a lopper at ground level, cutting away the old stems there. A few snips with a hand shears to shorten any stems that are too lanky completes the job.
Timing, for flowers
A second problem with this pruning/butchering job was timing. Forsythia blooms first thing in the spring, not on shoots that start growing early in the season but on stems that grew last season. So anything cut off now translates to that many fewer flowers next spring.
For the most abundant flower show from forsythia or any other early-spring flowering shrub, wait to prune until after the burst of colorful blossoms subsides, in the spring. (Summer blooming shrubs, such as butterfly bush and rose-of-sharon, blossom on new shoots, so nothing is sacrificed by cutting off old ones in winter or anytime before growth begins.)
Timing, for health
Fall or early winter is also not the best time to prune forsythia or any other plant in terms of plant health.
Plants respond to being cut with a certain amount of activity right at the wound. This time of year, the response is nowhere near as obvious as the quick closing of wounds or new shoot growth that occurs in spring and early summer, but something, perhaps only on a cellular level, does nonetheless happen.
Plants are best able to face winter with their "machinery" shut down. Any place there is activity is liable to suffer cold damage in the months ahead. For this reason, wait to prune any plant until after the coldest part of winter has passed. And for plants that are particularly tender to cold, wait even longer, until just before or after growth has begun for the season, depending on when the plant flowers.
Time heals all wounds
There really was no critical need, however, to come screeching to a stop in front of those forsythia bushes being butchered/pruned. Forsythia is tough, not particularly susceptible to cold damage. Butchering can ruin its form and sacrifice part of next spring's show, but it won't harm or kill the plants. And with correct and timely pruning, forsythia bounces back to the glorious plant it wants to be.