Is there a house behind that shrub?

January 25, 2007

BY CHARLIE NEUMEYER - VICTORIA COUNTY MASTER GARDENER
EDITED BY CHARLA BORCHERS LEON


While gardeners are planning for next spring and summer, among the many chores on the to-do list is pruning the shrubs around the house or in the garden.

According to Skip Richter, Travis County Extension Horticulturist, "Pruning is perhaps the least understood and most abused of all gardening chores."

Some people just whack back shrubs with no clear idea of the purposes or the correct techniques for pruning.

PRUNE WITH A REASON

Dr. Douglas F. Welsh, a noted Texas A&M landscape horticulturist, points out that "pruning essentially involves removing plant parts to improve the health, landscape effect or value of the plant."

Once you have established a reason for pruning and understand plant growth habits, you will be ready to start the job and be assured of satisfactory results.

Let's take a look at each of these reasons.

Plant health

Maintaining plant health probably presents the most obvious reason to prune. Dead branches are unsightly and can be removed at any time. It is also important to remove dead material to prevent the spread of disease and to remove possible entry points for insects.

Another area of concern is branches that cross each other. As the wind blows, the branches will open wounds in the plant that will also allow insects to enter.

Late February or early March - before budding - is the best time to remove live and/or injured limbs. Pruning will also stimulate new growth and increase the plant's vigor. And lastly, removing old and weak limbs will improve both the plant's health and appearance.

Keeping in shape

In the landscape, perhaps the most common reason for pruning is to improve or maintain the shape of plants. All too often, the ultimate size of a shrub was not a consideration in the initial planting plan. We choose planting material because our parents had a specific shrub or because it was less expensive or, as is often the case the plant was there when we bought the house.

After a year or two, the plant has outgrown the space and is no longer an asset. If the planting is a formal hedge, regular pruning is needed to maintain the shape. If the planting is informal, the pruning can be done less frequently, but a yearly pruning will help maintain the natural shape of the plant.

Fruit or flowers

We grow many plants for their fruits or flowers.

According to Dr. Welsh, by reducing the amount of wood, "pruning diverts more energy into the production of larger, though possibly fewer, flowers and/or fruit."

Generally speaking, plants that flower in the spring should be pruned after they flower; plants that bloom after June should be pruned in late winter or early spring. 

Tools of the trade

The correct tools make any job easier, and that certainly applies to pruning. Nurseries carry a wide variety of tools, and the gardener will need a few common tools to complete the job.

A good pair of pruning shears is essential. These shears come in two types: one type is a bypass shear, which has a scissor-like action. The other type is an anvil action shear. With this type, a sharp blade cuts against a broad blade. Either type will work well on limbs up to a half inch in diameter.

Moving up in size, the next shear is the lopping shear. These shears have long handles that add power to the cut. A good pair of lopping shears can cut limbs up to 2 inches in diameter.

For maintaining hedges, there are two options: manual and electric. Both have their places. The manual hedge shears are useful for clipping small bushes or hedges. They generally result in a cleaner cut and the shears are easy to control. Electric hedge shears are useful if there is a broad expanse of hedge to maintain. While they may mangle some limbs and often get stuck on thicker limbs, they can be a real time saver. Just remember, always wear heavy gloves when using the electric shears and keep the cord out of the way.

Another useful tool is a pruning saw. A razor tooth handsaw is a good investment and can easily handle limbs that are 2-4 inches in diameter. Because of the small blade width, they can be used in tight places and are very useful when major pruning is needed. 

Pruning techniques

For gardeners looking for a low-maintenance landscape, informally trained and shaped plants are ideal. To maintain a plant's natural shape, Texas Cooperative Extension recommends thinning out, gradual renewal and/or rejuvenation pruning.

To thin out a shrub, remove a branch or twig at its point of origin from the parent stem. This method opens up the plant allowing light and air to circulate through the plant. It can control the height of a plant if the oldest and tallest stems are removed first.

The pruning shears, loppers and the handsaw are the best tools for this type of pruning. Gradual renewal pruning focuses on the oldest and tallest branches. These limbs should be removed at the ground level each year. The most drastic type of pruning is the rejuvenation pruning. If the shrub is old and very overgrown, remove a third of the oldest and tallest branches slightly above ground level.

For gardeners who prefer more formal hedges such as boxwood or holly, regular pruning is required. Pruning for a formal hedge should begin immediately after planting. Never wait until the hedge has grown to its desired height. No matter the shrub, the guidelines are the same. The base of the hedge should always be broader at the bottom than at the top. This allows light to get to the leaves at the base and will eliminate weak or thin growth at the bottom.

However, if a hedge has gotten too large (see photos), a more drastic approach is needed. In this situation, prune to 1 foot below the desired size. This should be done in spring before new growth appears. This may not work on all evergreen plants, but boxwood and yew should respond well. 

Groundcovers

Groundcovers are perhaps the most easily pruned landscape plants. Simply set your lawnmower at its highest mowing level and have at it.

According to Dr. Welsh, honeysuckle, winter creeper, Asian jasmine and English ivy can be mowed with a rotary lawnmower to keep it "vigorous, neat and well manicured." This pruning should be done in early spring.

Pruning does not have to be an arduous task. The right equipment is a major asset. Correct timing for pruning can spread the job over the course of a year so that all of it does not have to be done in the spring. And remember, those clippings and limbs can be recycled into mulch or made into compost.
For Gardeners who prefer more formal hedges such as boxwood or holly, regular pruning is required for shape.  This untrimmed English boxwood shrub has grown too large for the planting site.

ALL PHOTOS BY CHARLIE NEUMEYER,
VICTORIA COUNTY MASTER GARDENER

SHRUB PRUNING TIPS

January 25, 2007

PRUNE IN LATE WINTER

Butterfly bush

Shrub althea

Hills of snow

Crape myrtle

Chaste tree (vitex)


Prune after blooming

Japanese quince

Redbud

Fringe tree

Forsythias

Honeysuckle

Indian hawthorn

Azaleas

Viburnum


Helpful Pruning tools

Bypass or anvil pruning shears

Lopping shears

Electric or manual hedge shears

Pruning saw
When a shrub or hedge has gotten too large for its site, prune to 1 foot below the desired size. This should be done in spring before new growth appears.
Notice the new growth on the boxwood 18 months later. The plant has been pruned to control the shape.