Pruning Perfection

Daniel Gill, Merrill, Thomas A.  |  10/4/2004 4:26:00 AM

Now is an excellent time to evaluate your landscape for pruning that needs to be done, since many plants can be pruned in February.

When it comes to this gardening task, practice is one of the better teachers. But there are a few general rules you can follow.

Plants that may be pruned during the winter and early spring include most woody plants, such as fruit trees and other trees, shrubs, hedges and foundation plantings that are not grown for their flowers.

Although both evergreen and deciduous plants may be pruned, for trees and shrubs that are grown for their flowers, you must consider when they bloom before you decide to prune them.

Avoid extensive pruning this time of year of spring-flowering ornamental trees and shrubs (those that bloom from January through April), such as Japanese magnolia, silverbell, 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.

Summer-flowering trees and shrubs, such as crape myrtle, vitex, althea, oleander and abelia, may be pruned now, since they will set flower buds on new growth they produce next spring and summer.

There also are a few shrubs, including gardenia, hydrangea, some old garden roses and many climbing roses, that are in a category of their own. They bloom in early summer, but they produced their flower buds or flowering shoots from last year’s growth. Extensive pruning done from now until they bloom will greatly reduce or eliminate flowering. Prune these plants in mid-summer – soon after they have finished blooming – to avoid problems.

Once you have decided to prune, the real dilemma is exactly how to do it.

Most gardeners feel they don’t know what they are doing, and they are afraid of damaging or killing the plants they prune.

Admittedly, there often is no simple answer.

Fruit and nut trees are best pruned in particular ways to control growth and encourage abundant, high quality fruit. For these plants, you should seek appropriate information in books or references for specific recommendations on how to prune them.

In most instances, however, a book cannot tell you exactly how you should prune a particular plant in your landscape. Each plant is different, the desires and needs of each gardener are different and each situation is unique.

General advice about pruning shrubs – such as telling you to try to maintain the natural shape of the plant – is good, but it’s not always that helpful to someone trying to learn how to prune or to figure out if they’re doing it right.

When learning, you can, however, at least make sure you prune at the proper time and become familiar with the basic pruning techniques we use to shape and control plants.

Here are some of those techniques:

–Heading back involves shortening shoots or branches and stimulates growth and branching. Heading back often is used to control the size of plants, encourage fullness, rejuvenate older plants and maintain specific shapes – as in topiary and espalier. Often overused by gardeners, careless heading back can destroy the natural form of a plant.

–Shearing is a specialized type of pruning that is done with pruning tools called shears or hedge trimmers. This technique is a variation on heading back and is used to create geometric shapes, espalier or topiary common in formal landscape designs. Shearing tools should not be used for general pruning purposes such as controlling size. The result will be clipped formal shapes, which require a lot of work to maintain.

–Thinning out removes shoots or branches at their points 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. Practice makes perfect, as that saying goes.

The first step to gaining confidence is to ask, and fully answer, two questions before pruning begins.

First ask specifically why you feel this plant needs to be pruned. What specific goal do you want to accomplish? What problem do you need to correct?

Of course, if you can’t come up with a valid reason to prune a plant, leave it alone.

But if you have a good reason for pruning the plant, ask the second question, which is 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, general recommendations regarding pruning.

–Prune only if necessary and use proper and sharp pruning tools. It is better to prune regularly, as needed, than to prune severely only when things get way out of hand. I almost always carry my pruners with me when I work in my garden.

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

–Do not prune shrubs and hedges late in the year between September and December, because the new growth stimulated by such pruning 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.

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

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