Rejuvenating Overgrown and Aging Shrubs

Don’t be so quick to uproot and throw away those shrubs that have outgrown their space or become leggy and unattractive. In many cases, with some pruning and fertilizing, you can give those venerable troopers a new lease on life. Unless the plant has reached the end of its natural lifespan, most older yet healthy shrubs can be brought back into scale with the rest of the garden.

Shrub renovation is not for the faint-hearted. You must be prepared to do some heavy pruning, in some cases cutting the plant right back to the ground or to a few bare stubs. It also requires patience. It can take several years for a tired, overgrown shrub to be restored to a youthful looking thing of beauty.

There is always the possibility that the shrub you try to revive will not survive. If you plan to work on an unusual or hard-to-replace specimen, propagate new plants as a backup before you begin work. To enhance the chances of severely pruned shrubs making a good recovery, feed and water them well the following growing season. With the what ifs in place, you can safely get started.

REJUVENATING DECIDUOUS, FLOWERING SHRUBS

The best time to prune flowering shrubs is shortly after they’ve bloomed. While some shrubs, such as red twig dogwood (Cornus alba) can be completely down to the ground and regrow, a general safe rule of thumb for most deciduous shrubs is to cut one-third of the branches down to the ground or the main stem the first year, another third the second year, and the final third the last year. Choose the oldest and least desirable stems to remove the first year, but also remove stems from all sides of the shrub so you maintain a balanced form. While you are pruning in the second and third years, remove new growth that is weak or that will spoil the shrub’s form and balance.

To reduce the size of an overgrown shrub, cut the oldest stems right down to the ground as described above. Also remove all dead branches. Be sure to leave enough stems to provide energy to the plant. Then trim back the remaining stems to just below the ideal height you have in mind. Once the shrub grows back enough to cover the pruning wounds, establish a maintenance pruning routine to keep the shrub in shape.

RENOVATING BROADLEAF EVERGREEN SHRUBS

In warm, southern climates, you can renew shrubs such as rhododendrons, azaleas, and mountain laurel by cutting them back to the ground. Old boxwood, which can live for hundreds of years, also has a good chance of living when treated to this drastic measure. Survival is enhanced if the plants are given a heavy dose of cottonseed meal and manure at least a year before the radical surgery, and are kept well fed and watered afterward.

For plants you absolutely don’t want to put at risk, rejuvenate the shrub gradually by cutting back about a third of the branches at a time, spreading the operation over three years. Choose the longest, most ungainly branches first, cutting them back to their point of origin.

Whether you cut the plant down to the ground or remove the old growth in stages, do the job in late winter or early spring when the plant is bursting to send out new shoots.

RENOVATING HEDGES

Some of the best hedging plants include boxwood, holly, hornbeam, and yew because they are slow-growing and long-lived. If you have an overgrown hedge comprised of any of these plants, it is well worth your time and trouble to restore it. While the hedge will look odd for several years while the restoration is going on, you’ll have an attractive hedge again much sooner than if you start over with young plants.

Begin in late winter by cutting the top back to the height you want, cutting back to bare branches if necessary. Next, severely prune just one side of the hedge, cutting it back to the main stem or stems. Leave the other side untouched. Feed the shorn plant with a balanced fertilizer and top dress with compost or manure. To protect the now-vulnerable shrub, water deeply if the weather gets dry, then add a thick layer of mulch to help maintain even moisture.

Wait until the pruned side of the hedge is showing vigorous growth before you cut back the other side. You may need to wait two or three years to insure that the plant is strong enough to take another shock. Once you think it’s ready, cut back the second side, following the same procedures as you did for the first.

Rejuvenating old shrubs is well worth the trouble for mature plants that still have good years left in them. Give it a try.

Article written by guest blogger Catriona Tudor Erler.