When and how do you prune an overgrown forsythia?

A Question of the Week
forsythia in bloom

Forsythia is a favorite shrub in the spring landscape with its cheery yellow flowers that bloom before most other trees and shrubs. Forsythia bloom is one of the first hopeful signs of spring, which is undoubtedly why it is so widely planted.

However, though breathtaking in the spring, forsythia shrubs can become an overgrown mess if they are not regularly pruned. Forsythia grows very quickly in an unkempt fashion, sending out suckers and upright-arching branches in every direction. Since the flowers are the only notable ornamental feature, it is important to prune at the right time of year in order to maximize bloom.

Forsythia produces flower buds on current season’s growth, so if you want to maximize the flower show, prune shrubs shortly after they finish flowering. All pruning should be completed before mid-July in order to give plants enough time to put on new growth and develop flower buds.

Pruning is often regarded as one of the most intimidating aspects of gardening, but pruning forsythia should not cause too much anxiety. Because it is such a fast-growing shrub, pruning errors are hardly permanent and can be corrected in subsequent years. Nonetheless, pruning will be most beneficial to the shrub if it is done with thoughtful intent.

Tools Used to Prune Forsythia

Proper pruning starts by choosing the right tools for the job. Pruning shears (hand pruners) can be used on branches that are up to a half-inch in diameter. Because they work like scissors, hand pruners are the most efficient tool for cutting small branches. It can also be helpful to have a quality pair of loppers on hand to cut stems that are up to an inch in diameter. A small pruning saw is useful for slightly larger branches. Hedging shears should never be necessary on forsythia. Although shearing is faster than hand pruning, selective hand pruning with the other tools mentioned is much better for the plant and more attractive.

How to Prune Forsythia

An overgrown forsythia can be pruned in a couple of ways. One option is to remove a third of the oldest branches shortly after flowering in the first year, followed by half in the second year and the remainder in the third year. Cut branches as close to the ground as possible to encourage new growth to emerge from the base. Use this approach if the forsythia serves as a screen or an important backdrop in the garden. A more severe approach is to cut all of the branches to the ground and let the shrub resprout. This type of total rejuvenation can be done every three to four years in order to keep growth in check and achieve the tidiest possible look to the shrub.

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