A shrub is a multistemmed plant (Figure 11-8). Its branches and twigs differ in age, with the best flower and fruit production usually on the younger branches. The younger branches are usually distinguished by a lighter color, thinner bark, and smaller diameter. The point at which the branches and the root system of a shrub meet is the crown. New branches originate at the crown, causing the shrub to grow wider. New shoots may arise from existing roots or from prostrate stems, termed stolons, to create new shrubs from the parent plant. In some grafted plants, the graft union may be seen at or near the crown. (Grafting is described in Chapter 14.) Shoots originating from the stock (or root portion) of a grafted plant are cut away since the quality of their flowers, fruit, and foliage is inferior. Only shoots originating from the scion (or shoot portion) are allowed to develop.
The Proper Time to Prune
Landscapers who design and install as well as maintain landscapes usually prefer to prune when they have little other work. This distributes
Stolon
(on the surface)
figure 11-8. The parts of a shrub (Delmar/Cengage Learning)
their work and income more evenly throughout the year. Some plants can accept this off-season attention and remain unaffected by it. Other species accept pruning only during certain periods of the year.
There are advantages and disadvantages to pruning in every season. Since seasons vary greatly from region to region, the following can be used only as a general guide to the timing of pruning.
Winter Pruning Winter pruning gives the landscaper off-season work. It also allows a view of the plant unblocked by foliage. Broken branches are easily seen, as are older and crossed branches. The major disadvantage of winter pruning is that without foliage it is difficult to detect dead branches. Because of this, plants can become seriously misshapen if the wrong branches are removed. An additional disadvantage is the damage that can be done through cracking frozen plant parts.
Summer Pruning Summer pruning also provides work during a slower season for the landscaper. An advantage of summer pruning is that it allows time for all but very large wounds to heal before the arrival of winter. The major limitation of summer pruning is that problems of plants may be concealed by their full foliage. Branches that should be removed are often difficult to see. Especially with trees, it is difficult to shape the branching pattern unless all the limbs are visible.
Autumn Pruning Pruning during the autumn season may conflict with more profitable tasks for the landscaper. In terms of the health of the plant, autumn pruning is acceptable as long as it is done early enough to allow cuts to heal before winter. Autumn pruning should not be attempted on plants that bloom very early in the spring, however. These early bloomers produce their flower buds the preceding fall. Thus, fall pruning cuts away the flower buds and destroys the spring show. Autumn pruning should be reserved for plants that bloom in late spring or summer, producing their buds in the spring of the year.
Spring Pruning Since spring is the major planting season, most landscapers do not welcome pruning requests unless maintenance is their principal business. However, most plants are most successfully pruned
during the spring. As buds begin to swell, giving evidence of life, it is clear which are the live and dead branches. Furthermore, there is little foliage to block the view of the complete plant. Spring pruning provides the plant with maximum time for wounds to heal. In addition, the unfolding leaves conceal the fresh cuts from the viewer’s eye.
If the plant is an early spring bloomer, it is best to prune it immediately after flowering. Plants that have a high sap pressure in the early spring, such as maples, birches, walnut, and poinsettias, should not be pruned until summer or fall, when the sap pressure is lower. Otherwise, the excessive exudation becomes unsightly.
