Plants pruned as a solid hedge should be wider at the bottom than the top.
Trees and shrubs may be looking shabby, but don’t prune them now. Although light pruning can be done any time of year, pruning at the wrong time of year can cause cold damage to your plants.
Pruning done in the late fall or early winter stimulates new growth, especially if we have a mild winter. This new growth is very tender and is easily damaged, even by a light frost. So it is much better to wait until spring before pruning. This will reduce the risk of cold damage.
But wait, there is even more to know before you start pruning in late February or early March. Plants that set their buds on old wood must be pruned AFTER they bloom. These plants set their flower buds on the previous year’s growth, the buds overwinter and then they flower in the spring. Plants that bloom on old wood include azalea, magnolia, Indian hawthorn and some hydrangea. To get the most flowering from these plants, wait until after their spring bloom to prune. Begin pinching the new shoots as they grow. This pinching will give the plant lots of lateral (side) branches, which can then develop flower buds for a spectacular bloom next year. Buds will start to form in July, so stop pruning after June.
Plants that produce flowers on this year’s growth are usually pruned while dormant (January/February), or just before the spring growth flush. These plants include crape myrtle, hibiscus, allamanda, plumbago, frangipani and rose. To encourage the most plant growth, prune just prior to the first spring growth flush. To slow growth and keep plants smaller, prune just after each growth flush. Again, pinching of new growth will encourage lateral branching, and thus produce more flowers.
Most evergreens, such as podocarpus, holly, ligustrum, juniper and wax myrtle, can be pruned anytime. Terminal growth of pines can be controlled by removing one-half of the candle (new shoot) in the spring just prior to needle expansion. This encourages new bud formation at the pinch, slows growth on the pinched branch and creates a more compact plant. New buds will not form behind pruning cuts made into older wood.
Pruning wounds callus (scab) the best when cuts are made just before, or immediately following the spring growth flush. Quick wound closure is important for keeping insects, diseases and decay organisms from entering the plant, and it also looks better. The smaller the diameter (size) of the branch that is cut the better it is for wound closure. Aim to only trim those branches that are about the thickness of a finger or less. When large branches are removed there is a higher likelihood that disease rotting organisms or other pests will enter the wood and cause problems as time progresses. Another good rule to follow is to only remove one-third of a plant’s entire mass when pruning.
The first step in pruning a shrub is to remove all dead, diseased, or injured branches. Also, remove branches that cross or touch each other, or those growing haphazardly. Cut each branch separately to different lengths with hand pruners. Cut back long branches to a bud or lateral (side) branch 6- to 12-inches below the desired plant height. When heading (cutting back) terminal shoots, make the cut on a sight slant one-quarter inch above a healthy bud. The bud should be facing the direction you want the branch to grow. Pruning in this manner creates a beautiful shrub that does not show any pruning cuts.
When pruning for a formal hedge, pruning should be done while the new growth is green and tender. Always prune so that the base of the hedge is slightly wider than the top. Think of a Christmas tree shape – wider at the base than at the top. It’s best to cut each branch separately rather than using hedge shears.
To keep from spreading disease, always clean pruning equipment with a disinfectant before using on a new plant. If pruning diseased branches, clean equipment before moving to the next branch.
A good disinfectant to use is a 70 percent to 100 percent alcohol solution.
For more information Google: “Pruning Landscape Trees and Shrubs IFAS” or “Disinfection of Horticultural Tools IFAS”
For free help with your lawn and garden questions, the Pinellas County Extension Service is just a phone call or visit away. We are located at 12520 Ulmerton Road, Largo next to the Florida Botanical Gardens and open from 8 a.m. to 5 p.m. Monday through Friday. To speak with a horticulturist call 582-2110 Monday, Tuesday or Thursday from 9 a.m. to noon and 1 to 4 p.m. You also can visit our website at www.pinellascountyextension.org.
Jane Morse is a University of Florida/IFAS, Pinellas County extension agent.