Acacia trees (family: Fabaceae) are tall semi-evergreen trees with feathery leaves and small beautiful yellow flowers that grow as clusters. Acacia is a native of North America. Some species of Acacia possess long and sharp multiple thorns. They can grow well in any soil, provided it is not wet. Depending on the nature and type of the soil, Acacia trees grow up to a height of 70 to 80 feet and a diameter of 3 feet or more. Acacia trees are shady trees that are usually planted in parking lots, near highways, and they are even used as residential street trees.
Pruning of Acacia Trees
Pruning is a horticultural practice that changes the style and growth of a plant. Young Acacias should be pruned periodically for healthy growth. Pruning during the formative years prevents many growth-related problems.
At the time of planting, only the diseased, dead, or broken branches are removed. Formative pruning can be done to a standard tree as well as a multi-stemmed bush. It is better to prune Acacia in April, after the winter. This will encourage the growth of the tree during summer.
Acacias grow with a central leading branch. Usually, these leading branches are not pruned as this may spoil the shape of the tree. Acacia plants require periodical pruning throughout its development stages. Also, an accacia can be trained as a multi-stemmed bush.
Pruning: Standard Tree
During the first year, remove side shoots that sprout from the middle part of the main stem. Also remove branches from the lower main stem and dead, damaged or diseased growth from the top stem. To avoid the center growth, cut the outward facing buds in order to encourage their growth.
During the second and third years, remove the branches from lower stem, which were shortened during the first year. Remove the misplaced branches in the upper part of the stem. Shorten the side shoots that sprout at the middle part of the stems.
During the fourth and fifth year, clear the canopy by removing dead, diseased or misplaced branches. Shape the trunk of the side branches to the desired height.
After the fourth year, carry out pruning as that for a matured tree.
Pruning: Multi-Stemmed Bush
This method is suitable for the vigorous or suckering species of Acacia. Cut the main stem of a 2-year-old tree at the desired height, and trim the wound so that there are no rough edges.
During the second year, retain 2 or 3 strong and well-spaced, regenerated branches, but remove the remaining regenerated branches. During the third and fourth years, remove the new stems sprouting from the base, and thin out the congested branches. Also remove side shoots dragging on the ground.
Pruning: Mature Acacia
Mature specimens require less pruning. Prune the following in spring:
- Side shoots that sprout just below the faded flowers and flower into 2 or 3 bud
- Branches damaged due to frost
- Extremely congested plants
- Branches that spoil the shape of the plant.
Overall, the best time to shape the Acacia is after the flowering period. Pruning at this time increases the life of the plant.