Master Gardener: Pruning to promote plant health and beauty
For many gardeners, pruning is a topic that makes us nervous. That’s probably because the subject is laced with “ifs,” “whens,” and “hows.”
First, should we prune? For fruit producers and most shade trees, the answer will be “yes.” For perennials, shrubs, and evergreens, “maybe” is more apt.
Determining when to prune depends mostly on the particular plant variety. For fruit trees, grapevines, and raspberries, late February or March is ideal; with the long, cold winter this year, finishing up in very early April should be fine.
For spring-bloomers such as forsythia, lilacs, and crabapples, the answer will be “not now.” Wait until the blooming season is past. However, do prune suckers or shoots at the base of these plants, and remove any dead or broken branches as soon as you identify them.
Most shade trees can be pruned now. However, for oaks and walnuts, wait until summer as a disease-prevention strategy.
Normally, this would be a good time to prune evergreens. If you are pruning them to control size, then it is fine to go ahead. However, if you are pruning out dead branches, wait until the end of May this year to determine what is really dead.
Timing for perennials depends on the species. Japanese spirea and butterfly bush, for example, can be cut back almost to the ground in early spring. Hydrangeas and clematis present trickier timing issues. Those cultivars blooming on new growth only can be pruned to the ground; if a particular plant blooms on old growth, however, you will want to leave those branches alone.
Smooth hydrangea such as ‘Annabelle’, for example, bloom on new growth only, so they can be pruned to ground level. However, varieties such as ‘Endless Summer’ bloom on both new and old growth. For such varieties, wait until plant growth begins and prune out only the dead branches. An online search, even by your plant’s common name, will tell you whether it blooms on new or old growth.
The important qualifier for how to prune is carefully. Do not, for example, tackle a very large tree; instead, for your own safety, turn to professionals or utility companies to handle it.
As you prepare to prune, be sure that your equipment is in good order. A pruning saw, loppers, and shears will all prove to be valuable if they are clean, rust-free, and sharp.
Work slowly, and check the overall effect often. Pruning mistakes cannot be undone! For trees and shrubs, your aim should be to preserve the basic form while opening up the canopy for good air flow.
To find a model of correct pruning cuts, consult a comprehensive guide or visit an excellent, well-illustrated website such as www.hort.purdue.edu/ext/ho-4.pdf.