Pruning becomes necessary as shrubs mature to maintain the original landscape effect desired by planting the shrubs. Pruning is almost always successful in Late Winter, however, it is important to consider flowering cycles. Plants like Azaleas need to be pruned immediately after flowering. Since they flower on last year’s new growth, late pruning will remove the flowers for next year. Roses and Crepe Myrtles need to be pruned in Late Winter because these plants flower on the new growth of the season. Generally, if you are pruning flowering shrubs it is best to do so immediately after the flowering cycle is complete.
If you are pruning to control size it is best to remove 1/3 of the limbs each year for three years to reach the appropriate height. In this process simply cut back only the long limbs leaving the shorter ones. This process is called selective pruning and is always the best method to promote plant health.
Shearing shrubs to maintain a ball shape is never recommended because this process reduces the size of flowers, and causes the leaves to only be found in the outer inches of the ball. The limbs are barren on the inside and air circulation is reduced. This encourages insect and disease development. Also, the lower parts of the ball are shaded out causing an umbrella effect.
We don’t recommend shearing, however, if you do your plants will be healthier if you do not box or ball when you shear. If you must shear we prefer that you leave your shrubs upside down “V” shaped on top rather than flat and sloping out “Christmas tree style” on the lower parts. This process will help your shrubs maintain fullness down to the ground. The ever remaining problem with shearing is the shrubs tend to lose limbs and this leaves you with gaping holes in the shrub on the outside.
Again, in selective pruning, you can maintain your plant’s size and help your shrubs to have a more natural appearance. Remember it is risky to the life of your shrubs to prune too deeply when you are trying to drastically reduce the size of overgrown shrubs. If you are doing drastic pruning please do it in Late Winter just before the sap rises in the Spring. This is the time when survival is best for larger shrubs.
Some shrubs have inherent disease problems. The Rose family is the worst for this including Red Tips and Indian Hawthorn. If you are pruning these shrubs it is best to clean your pruners between plants to help reduce spreading systemic diseases throughout the row. Washing with soap and water or dipping in rubbing alcohol should be sufficient to sanitize the pruning equipment.