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Eucalyptus, Coral Trees True to Form

SPECIAL TO THE TIMES; <i> Ann Christoph is a landscape architect. </i>

Coral trees and eucalyptus are among the most memorable trees of the Orange County coast. But these trees, which have the potential for such beauty, are also among the most maligned by poor pruning.

Kaffirboom coral trees, when allowed to mature properly, grace the landscape with their exotic-looking muscular trunks, and clusters of red flowers on bare branches. Seen at a distance, eucalyptus trees provide beautiful skyline silhouettes in contrast to the coastal hills, sky and ocean, and their delicate canopies and intricate branch structure lend an informal sheltering ambience in many areas.

Perhaps because we often want our landscapes to look mature as quickly as possible, these trees are frequently abused.

Corals and eucalyptus have a reputation for fast growth, and they do become good-sized trees within a few years. The problem is that they continue to grow rapidly to reach ultimate sizes of 40 feet tall by 60 feet wide for the Kaffirboom coral (Erythrina caffra), and up to 80 to 100 feet tall for some eucalyptus.

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After the “few years” have passed and the trees have begun to outgrow their space, the hackers are called in, and the result is pruning jobs that will never allow the trees to develop their natural form.

How to avoid this?

* Before you plant, research trees to select the best tree for the space available. For a confined space, select a slower growing, smaller statured tree. For corals, a naked coral tree (Erythrina coralloides) or a Natal coral tree (Erythrina humeana) should be considered. These reach only 30 feet instead of 60 feet. There are also smaller scaled eucalyptus such as Eucalyptus lehmannii (bushy yate), ficifolia (red flowering gum), and erythrocorys (red cap gum).

* Minimize the need for pruning by choosing and placing the tree with consideration for future effect on light and views (both your own and your neighbors’).

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* When pruning is needed, remember that each type of tree has different characteristics and growth habits, and different timing and techniques are required.

Corals bloom on the old wood. Consequently, they should not be pruned before blooming. Typically in Orange County, pruners go out in the fall and severely cut back the ends of all of the branches. This removes all of the flower buds, which would open in late winter. The tree responds by trying to recover from this severe pruning and produces a flush of new growth (water sprouts or suckers).

This overloads the tree with thick bunches of leafy branches that will not flower and that will “need” to be cut again the following year. The result is a misshapen tree that never produces the flowers the tree is known for.

Instead, prune lightly after the blooming season ends to remove crossed or redundant branches or to correct structural problems. The size of the canopy can also be somewhat controlled by consistent, careful removal of extending branches. Severe “heading back” should not be done.

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Pruning of eucalyptus is not limited by season, although thinning the tree’s canopy in preparation for the Santa Ana wind season is a good idea.

Thinning should be done by selective removal of branches back to where they join the trunk or main branch. Do not leave stubs, and do not “top” (cut off a main leader branch, leaving a thick cut trunk). Leave the lower and pendant branches where possible, as they help to develop the character of the tree. This will also help to distribute the growth throughout the tree, make for a stronger branch and trunk structure, and reduce the tendency for too fast upward growth. Guiding the growth of eucalyptus as it develops from a small container is critical to developing the desired form of the tree.


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