This is a good idea if your bush is large and unruly and you want to tame it back. You may sacrifice a season of flowers, but your forsythia bush will look much better the next year.
Letting the plant take its natural shape helps it establish a healthy root system.
The largest stems have the thickest diameter. The oldest stems typically are also the tallest. By getting rid of them, you reduce the overall height of your shrub. If you can’t reach the very middle of the shrub’s base, cut it to 3–4 in (7. 6–10. 2 cm) from the ground. Do this after your plants mature to about 5-6 years old. This way, they are large enough to support such a massive pruning. [5] X Research source
Trimming the top of the stem off helps reduce the height of your plant while promoting a spot for new shoots to grow.
If you don’t remove low branches, they may start to root to the ground.
If you notice any stems growing inward rather than outward, these should be pruned as well. Dead, bent, and split stems also change the look of your shrub.
Removing branches displays the natural shape of the plant. Keeping your forsythia open allows light and air into the middle of the shrub, which helps it grow healthy.
For best results, do this in late winter or early spring. Blooming will be reduced or nonexistent after a dramatic pruning. After a few years, your plant will look full again.
