Tip of the Week

Best time to prune

When is the best time to prune flowering trees and shrubs?

The answer depends on whether the plant produces flowers on old (last year's) or new (this year's) growth.

The following information on pruning comes mainly from two internet sources:

! gardening.about.com/ od/treesshrubs/a/PruneTreeShrubs.htm

! www.hintsandthings.co.uk/garden/pruning.htm

And before I begin, let me say right up front that far too many gardeners in East Texas perform "Crepe Murder," which is the cutting of crepe myrtles back to main trunks every fall.

This practice causes the plant to have fewer blossoms in the spring, makes a strange looking if not downright ugly plant, and causes spindly new growth each spring.

Like other trees, crepe myrtles should be pruned only by selectively cutting out whole branches to maintain the shape of the plant. If a plant is too big for the space, take it up and plant one of the many varieties of a more appropriate size.

As for trees, no tree should be "topped" which is the cutting back of major limbs leaving several feet of the limb sticking out beyond the trunk.

Trees don't recover from this radical procedure, and they never bush back out attractively.

As with crepe myrtles, trees should be pruned by selectively cutting out limbs back to a major node. Trees should only be pruned to maintain shape (not size), to remove dead or diseased wood, or to keep limbs from contacting structures.

So, with that said, some trees and shrubs benefit from annual pruning. It keeps them in shape, gets rid of dead and diseased wood and encourages new growth. But timing is important, especially for the ones that flower.

Early spring bloomers set their flower buds the fall before. Pruning them early in the spring would mean losing some blossoms.

Most of the time this is not what you want.

However there are exceptions.

It's often easier to prune when you can see the shape of the plant, before the branches are masked by leaves. Trees and shrubs that are in need of a good shaping could sacrifice a few blooms to be invigorated by a spring pruning.

The most important reason for pruning flowering shrubs, and to a lesser extent trees, is to maintain a large portion of the plant as young, vigorous wood.

Since most flower buds are formed on current or previous year's growth, you can remove up to one third of the oldest wood annually to keep the plant vigorous. Such pruning will stimulate future flower and fruit development.

Many flowering plants, such as azaleas, produce more flowers if old flowers and fruit clusters are removed.

In general, here are some rules for pruning:

! Prune flowering shrubs that bloom in spring, within a month after flowering.

! Prune summer flowering shrubs between January and March, before new growth starts.

! To keep a base of a hedge leafy, cut into a pyramid shape in spring, so that the top is narrower than the base. If a hedge is pruned wider at the top than the bottom the lower part will be shaded and the foliage will fall off allowing the top growth to spread, compounding the problem.

! If a hedge is too dense, cut it back to the main stems on one side only. Let the hedge recover and produce new growth for a year, then cut back the other side.

! If the hedge has become too tall, cut back every second shrub to within a few inches of the ground. New shoots should sprout around the severed trunks. Cut back the remaining shrubs the following year.

! Privet, Holly, Berberis, Forsythia, Roses and Spiraeas respond well to hard pruning.

! For climbers that flower on new growth, e.g. Buddleia, Clematis Jackmanii, winter pruning is best.

! For climbers that flower on previous year's growth, e.g. early flowering Jasmine, Forsythia, Honeysuckle and ornamental Quince, prune after flowering.

! February is the best time to prune hybrid tea and floribunda roses. Cut out dead, diseased or thin wood and trim back the main shoots. When cutting back main shoots count buds from base of each shoot and cut just above the second or third one. The length of the shoot is less important than the number of buds.

! Shrub roses are best pruned in winter. As both old and modern roses produce most of their flowers on shoots produced from old wood, prune lightly. Remove dead, thin and decayed wood, and shorten main stems by about one third.

! Rambling roses should probably be pruned after spring/early summer bloom. Cut untidy, flowered shoots right down to the base and tie new shoots to the trellis or support. If there are only a few new shoots, leave some of the flowered shoots in place cutting back just a little.

! Climbing roses are also best pruned after spring/early summer bloom. Remove any crossing or thin shoots and reduce the height of the main stems by about one third. Remove any side shoots that spoil the shape and cut back the others by about two thirds.

! Miniature roses should be pruned in February. Cut off any dead, diseased or thin wood and trim back the main stems to about one third of their length.

In general, for East Texas, the following are guidelines for pruning:

Prune in late spring/summer soon after bloom. ! Azalea (Rhododendron species) ! Beautybush (Kolkwitzia amabilis) ! Bridal Wreath Spirea (Spirea x vanhouttei) ! Forsythia (forsythia x intermedia) ! Hawthorn (Crataegus species and cultivars) ! Hydrangea, Bigleaf (Hydrangea macrophylla)

! Mockorange (Philadelphus coronarius)

Prune in winter or early spring while dormant, but prune only for shape as too much taken off will affect next season's blooms.

! Butterfly Bush (Buddleia davidii) ! Crape Myrtle (Lagerstroemia indica) ! Flowering Plum (Prunus blireana) ! Glossy Abelia (Abelia x grandiflora)

! Honeysuckle (Lonicera fragrantissiam)

! Hydrangea, Peegee (Hydrangea paniculata `Grandiflora')

! Potentilla (Potentilla fruticosa) ! Spirea (except Bridal Wreath) (Spirea japonica) ! Wisteria (Wistera species)

Mary Hamlin, Smith County Master Gardener