The correct time to prune ornamental, fruit, shade trees and shrubs is dependent on their species and geographic location. For precise pruning scheduling it is best to contact either a competent nursery or the agriculture department of your local university. The following information is a guideline only.
- Coniferous trees and shrubs:
- Trees and shrubs that do not flower:
Coniferous trees (Figure 32) and shrubs, which include cedars, firs, junipers, pines and spruces may be pruned year around.& Pruning during the trees dormant season will lessen the flow of resins and saps from pruned limbs.
Figure 32 - Coniferous tree
This group of plants, such as maple, oak (Figure 33) and elm, should be pruned in their dormant seasons, usually late fall and early winter, for a number of reasons:
Figure 33 - Oak tree
- It is easier to see the natural form of the tree or shrub
- It is easier to prune due to limited foliage
- Allows for woundwood to form in the upcoming growing season
- Lessens disease transmission such as Dutch Elm and Oak wilt fungus.
- Reduces the amount of sap and resins that will flow from cut points.
As a general statement, trees and shrubs that flower should also be pruned in their dormant seasons for the reasons expressed above. However, there are some additional guidelines that should be used in order to maintain a yearly flower crop.
- Trees and shrubs such as redbud and dogwood (Figure 33a) are best pruned right after they flower. Flower buds should form on the new growth and open in the following spring.
- Trees and shrubs such as crabapple (Figure 34), hawthorn, pear, mountain ash and flowering quince are prone to a bacterial disease known as fireblight (Figure 35) that has a tendency to spread when the tree is pruned. To lessen the chance of spreading fireblight it is best to prune these types of trees and shrubs in their dormant seasons.
- There are a group of trees and shrubs that flower in the summer or fall and these plants should always be pruned in their dormant seasons. This will allow flower buds to be produced in time for the next growing season.
Figure 33a - Dogwood tree
Figure 34 - Crabapple tree
Figure 35 - Fireblight on ash tree
It is wise to obtain expert information from local sources before pruning these types of trees and shrubs.