The Best Time to Prune Forsythia

Renewal Pruning

• Ample pruning encourages forsythia to produce new shoots. Renewal pruning takes out some of the old wood so that the plant creates new stems in its place. A spring pruning allows the forsythia enough time to grow shoots, set buds and be ready to bloom the following spring. Remove about 1/3 of the larger canes in a renewal pruning to allow multiple new canes to emerge. Old, woody stalks with little to no leaves on them can be pruned to soil level. The plant will look forlorn and small, but it produces new shoots quickly. Renewal pruning can be an annual event.

Rejuvenation Pruning

• Some forsythia plants lose their shape, becoming scraggly and overgrown. Plants in this condition are candidates for an aggressive rejuvenation pruning. This method is also done in the spring, after the plant blooms, and it entails trimming all the stems to within 3 or 4 inches of the ground. It is a way to start fresh with a forsythia that has become mangled and ugly over time. Though the plant will look bad and may be slow to recover, new growth will appear over the summer. In the years following a rejuvenation pruning, forsythia respond well to annual renewal prunings.

Pruning Methods

• Trim shoots at an angle to allow them to weep moisture while the cut heals. Remove dead or diseased wood any time you prune, even if it means cutting the plant back further than you had anticipated. Plants divert much of their energy toward trying to fight disease or revive dying stems, energy that should go into creating new growth and blooms.

Response to Pruning

• Either renewal or rejuvenation pruning allows the removal of terminal buds, which send out hormones that prohibit lateral blooms and new buds from forming. Once terminal buds are gone, new growth over the summer will develop lateral buds that produce plenty of new blooms in spring. Forsythia may appear to go nearly dormant for a short period, especially after an aggressive pruning, but new growth will return vigorously once it begins.