For Release On Or After 01/21/11

By Dan Gill
LSU AgCenter Horticulturist

Pruning is a gardening job that is often neglected because gardeners are not exactly sure what to do. There is a great deal of confusion about how to prune, when to do it and even why pruning is done. Now is an excellent time to evaluate your landscape for pruning that needs to be done, and many plants can be pruned now through February.

Pruning is something you just have to get used to doing. Some plants won’t grow just the way we want them to, so they need to be shaped. And you’ll always have plants that grow larger than anticipated and need to be regularly pruned to control their size. Dead branches, diseased tissue and insect infestations may be pruned for the health of the plant. The list goes on. Pruning is simply a part of regular gardening activities.

Plants that may be pruned during the winter and early spring include many trees, shrubs, fruit trees, hedges and foundation plantings that are not grown for their flowers. You can prune both evergreen and deciduous plants.

Avoid extensive pruning of spring-flowering ornamental trees and shrubs that bloom from January through April, such as Japanese magnolia, silver bell, parsley hawthorn, Taiwan flowering cherry, quince, azalea, Indian hawthorn, deutzia, philadelphus, spirea, banana shrub, wisteria and camellia. They have already set their flower buds, and any pruning done before they bloom will reduce the floral display these plants will produce.

Crape myrtle, vitex, althea, oleander and abelia and other summer-flowering trees and shrubs may be pruned now because they will set flower buds on new growth they produce this spring and early summer.

A few early-summer-flowering shrubs, including gardenia, hydrangea, some old garden roses and many climbing roses, bloom on the growth they made last year. Extensive pruning done from now until they bloom will greatly reduce or eliminate flowering. Prune these plants in midsummer soon after they have finished blooming.

Once you have decided to prune, the real dilemma is how exactly to do it. Most gardeners feel they don’t know what they’re doing. Fruit and nut trees are generally best pruned in particular ways, and you should seek appropriate, specific recommendations when dealing with these types of plants.

In most instances, however, you’ll find no exact recommendations for how to prune plants in your landscape. Each plant is different, the desires and needs of each gardener are different, and each situation is unique. You can, however, at least make sure you prune at the proper time and follow some basic pruning techniques.

Heading back involves shortening shoots or branches and stimulates growth and branching. Heading back is often used to control plant size, encourage fullness, rejuvenate older plants and maintain specific shapes as in topiary and espalier.

Shearing is a specialized type of pruning done with pruning tools called shears or hedge trimmers. This technique is a variation on heading back and is used to create geometric shapes, clipped hedges, espalier or topiary common in formal landscape designs. Shearing tools should not be used for general pruning purposes, such as to control size.

Thinning out removes shoots or branches at their point of origin, either back to a branch fork or back to the main trunk. Thinning cuts can control the size and shape of a plant while doing a better job of maintaining the plant’s natural shape. Thinning cuts do not stimulate growth and often work more with the plant’s natural growth patterns to correct problems.

The only way to gain confidence in pruning is to do it. The first step to gaining confidence is to ask, and fully answer, two questions before pruning begins. First, why, specifically, do you feel this plant needs to be pruned and what problem do you need to correct? If you can’t come up with a valid reason to prune a plant, leave it alone. Second, how do you need to prune the plant to accomplish the goal? Study the plant carefully and decide what specifically needs to be done before you begin.

Finally, here are some basic recommendations regarding pruning.

– Prune only if necessary and use proper and sharp pruning tools. Generally, it’s better to prune regularly as needed than to prune severely only when things get totally out of hand. I almost always carry my hand pruners with me whenever I walk in my garden.

– Avoid pruning plants when they are under stress, such as in extremely hot, dry weather.

– Don’t prune shrubs and hedges late in the year between September and December; the new growth stimulated will not have time to harden off before freezes.

– If needed, extensive pruning should be done to spring-flowering trees and shrubs soon after they finish flowering.

– Prune most summer-flowering trees and shrubs in late winter.

– Remove dead growth anytime.

It is unlikely that you’ll kill or permanently damage a plant under most circumstances, even if you do something wrong when you prune. So, grit your teeth and go for it. The more you prune, the better and more confident you’ll become.