For:
By: Daniel E. Mullins
Extension Horticulture Agent
Better Lighten Up on the Fall Pruning
Unfortunately, some gardeners develop an urge to break out the pruning shears and cut back plants during the fall. With only a few exceptions, this is absolutely the worst time of the year to do heavy shrub pruning.
Shrubs such as hollies, camellias, azaleas and crape myrtles are in the process of entering a dormant stage. Let them stop growing and rest. Heavy fall pruning can stimulate a flush of growth at the wrong time of the year. The last thing that a gardener wants is a flush of tender growth with a freeze approaching.
Pruning jobs should be delayed until late winter or late spring, depending upon the species of plants. Group flowering shrubs into two categories – spring flowering and summer flowering, and plan to do any necessary pruning at the most optimum time.
Spring flowering shrubs have a rather unique pruning season. Since they form flower buds during late summer and fall during the previous year, pruning should be delayed until they are finished blooming in the spring. Examples of spring flowering shrubs include azaleas, camellias, forsythia, banana shrub, spirea, Indian hawthorn, wisteria and oriental magnolias.
Pruning these spring flowering shrubs during the summer or fall would remove flower buds and reduce the amount of color the following season. If pruned too early in the spring the number of flower buds would likewise be reduced in number.
To be safe, any necessary major pruning of spring flowering shrubs should be done as soon as the flowering season is over. An April or May pruning time is suggested because this allows time for plants to re-grow and develop flower buds on terminals.
The summer flowering shrubs on the other hand, produce flower buds on new, current season’s growth. The suggested pruning time is therefore seasonally the opposite of the spring flowering species.
Many
national gardening references simply recommend pruning them during the dormant
season without being more specific. The
problem is, under
Gardeners are encouraged to delay the pruning of the summer flowering shrubs until late in the dormant season, just before spring growth. In our area, this means late February or early March. Examples of summer flowering shrubs include abelia, hibiscus, crape myrtle, oleander, rose and althea.
Questions concerning the pruning of tender perennials have been common over the past two weeks. There appear to be two schools of thought, and practice, concerning this subject. Some cut them back to the ground before the first frost. The logic here is that they are going to be killed to the ground anyway. Other gardeners leave them alone and let Jack Frost do the pruning and the frozen parts are removed later.
The latter practice is recommended. To assume that all of the tops of tender perennials will be killed every winter is often a mistake. The sudden removal of the entire top of a healthy perennial removes much stored energy, a part of which might have moved down and been stored in the root crown. In addition those tops, if left on, can provide some insulation against the first few freezes.
Cold damaged growth can then be removed during late winter and early spring. By that time it is easier to determine how much pruning is actually needed.
Question of the Week: Can dormant oil spray be applied to peach trees now (November)?
Answer: It is too early for
applying horticultural oil emulsion as a dormant spray. Wait until mid winter and apply it before the
buds begin to swell.