Pruning is an important maintenance practice for some evergreens. However, pruning can be kept to a minimum by the wise use and proper placement of plant materials in the landscape design. Evergreen plants can be divided into two broad categories: (1) Narrowleaf (needled) evergreens such as pines, junipers and yews; (2) Broadleaf evergreens such as rhododendrons, hollies and box. The narrowleaf evergreens are generally grow more rapidly than broadleaf evegreens, include many tree forms and are commonly grown for their foliage only. Broadleaf evergreens include many shrub forms and are often grown for their flowers and fruit as well as for their foliage.

Why Prune?

Limit the pruning of most evergreens to the removal of dead, diseased and mechanically injured wood and to the maintenance of the natural shape of the plants. Formal effects such as clipped hedges, topiary and espaliers require regular attention and special equipment.

When to Prune:

Dead, diseased and broken wood can be removed at any time of year. The best time for general pruning is in late winter or early spring, immediately before growth resumes. Narrowleaf evergreens may be pruned a second time in June before the new growth has matured. It may be necessary to give particularly fast-growing plants an additional light pruning or two during the growing season. Good judgment must be exercised when pruning flowering evergreens so as not to drastically reduce the amount of next season's flowering woodÜany pruning should be done as soon after flowering as possible. Severe pruning can usually be avoided if pruning is done annually.

How to Prune:

It is important to have the necessary tools in proper working order for pruning your plants. These tools include a hand pruner, lopping shears, hedge shears and a curved pruning saw. Narrowleaf evergreens are characterized by growth that is either whorled or random (non-whorled). When pruning pines, make cuts just above the needle whorls. Most new lateral growth is stimulated at these points rather than along the stems between the whorls.

In pruning most other needled and broadleaf evergreens, cuts can be made at any point along the branch, but care should be taken not to cut too far back into the older wood, because new growth is not as readily produced from such wood. When selectively pruning, it is a good practice to cut the growth back to a side shoot. Some evergreen species withstand relatively heavy pruning. This is true of such plants as Japanese yew, box and evergreen privet. These plants can be sheared, which involves the uniform removal of new growth to make a plant conform to a prescribed shape. Because shearing encourages the formation of additional lateral growth, a more dense habit of growth is created. The amount and manner of pruning depend to a large extent on the type of plant, its location and the particular tastes of the homeowner.

Pruning Pointers for Specific Plants:

• Pines
Prune in early spring. Make cuts just above needle whorls. Additional pruning may be done before new growth hardens in June. Pines normally require little pruning.

• Spruces & Firs
Cuts may be made at any point along the younger portions of the branches. The best time to prune spruces and firs is in the early spring. Pruning is necessary to maintain the natural shape of the plants.

•  Juniper, camaecyparis and arborvitae
This group consists of many tree, shrub and prostrate forms. These species can withstand relatively heavy pruning and many may be trained into various forms by shearing. Early spring pruning is best, but additional light pruning later in the season may be necessary.

•  Yew and hemlock
It is preferable to allow these plants to retain their natural form, but both respond well to heavy pruning and shearing. Yews are able to withstand exceptionally severe pruning into the older wood. Early spring is the best time for pruning, although occasional light pruning later in the season may be necessary.

• Rhododendron, azalea, pieris and mountain laurel These plants generally require very little pruning, as they are slow-growing. Old flower clusters should be removed immediately after flowering. Prune out only dead, diseased, weak or wayward branches.

• Box, evergreen privet, barberry and pyracantha
With the exception of box, these species grow rather rapidly. All these plants will stand heavy pruning, which is best done in early spring. Because they are generally quite vigorous, additional trimming during the growing season may be advisable.

•  Hollies
These plants include both tree and shrub forms. American holly may be pruned in December for Christmas greens. Chinese holly is also a source of attractive greens and may be trimmed in the early spring. When pruning American holly, always make the cut at a node, just above a lateral bud. Prune so as to maintain the natural shape of the tree. The shrubby Chinese and Japanese hollies can be more severely pruned and may require some additional light pruning during the growing season.

• Mahonia and leucothoe
These are rather slow-growing plants which require little annual pruning--if pruning is necessary, do it immediately after these plants flower in the spring.

Adapted from the Delaware Cooperative Extension, 2000