Pruning Ficus benjamina

I have a 1-1/2 " diameter Ficus benjamina that is extremely happy but has grown to an unruly shape. It is located in a banker's office, and the officer would like to have the tree "ball" shaped. It has grown into a great big, droopy "Y". Is there a way to trim it back now without damaging it? - Celeste T.

I am reluctant to encourage the pruning of a tree to a form that is unnatural for the tree, but the tropical ficus, when well grown will tolerate many humiliations. It can be trimmed to a "ball" shape, but it will not remain in that form. You will need to prune occasionally to maintain the form.

As with all trees, I recommend proper pruning with regard to the major cuts; that is, don't top the tree. Prune a long branch back to its juncture with a smaller branch. Choose a branch that is at least one-third the diameter of the branch being cut. This smaller branch may also be pruned back in the same manner.

It is best for the tree if you make pruning cuts outside the "branch collar" (the swelling at the base of the branch) to avoid damage to the remaining portion of the tree. Pruning paints are not needed.

When you have the tree in the proportions you want, you can prune the remaining twigs back to a bud. As the tree grows, use this pruning technique of pruning twigs that are only one-to-two seasons old.

If a great deal of pruning is required, do the pruning over time. It is best not to remove more than 10 to 30 percent of the leafy bearing wood in a single growing season. The ficus may tolerate somewhat more pruning, but that depends on the health of the tree, the light conditions in the office, and other environmental and management factors. Don't fertilizer to compensate for heavy pruning. You may stimulate rapid regrowth at the expense of the tree's overall health and ability to resist diseases and insects.

Another consideration is to choose a tree that has a different form. Ficus retusa var. nitida is a more upright growing ficus and often more tolerant of office conditions than the Ficus benjamina. Since it is more upright (stiff-looking), it may form into the desired ball more easily than a tree that has a natural weeping form.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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