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Thursday - July 01, 2010

From: Coolidge, AZ
Region: Southwest
Topic: Pruning, Trees
Title: Runaway growth on mountain laurel in Coolidge AZ
Answered by: Barbara Medford

QUESTION:

I have 2 mountain laurels. They are thriving well. In fact one is growing way too fast. I am growing it as a tree, but the branches are in excess of 6 feet, while the trunk is only 18 or so inches. I have it tied to a post. The tree is only a year or so in ground and bloomed beautifully. I need to know when and how to prune it.

ANSWER:

Sophora secundiflora (Texas mountain-laurel) is not shown in this USDA Plant Profile as growing natively in Arizona, but obviously, you are managing very well. From Pima County Arizona Cooperative Extension, here is some more information on the Mountain Laurel. Another article, this one from Arid Zone Trees, Sophora secundiflora provides more on the culture of the tree, including the fact it should be pruned lightly, and excessive pruning avoided, as it only produces flowers on year-old wood. For this reason, we would recommend that whatever pruning you feel necessary should be done right after the blooming has finished. If you are trying to procure seeds, you will have to let the blooms mature to seed pods. We also know that it needs very good drainage, and cannot tolerate water on its roots.

As for the excess growth, watch the fertilizer. This is one of those desert plants that is really not too fond of fertilization. You probably don't need to fertilize it at all and, if you do, use a low-nitrogen fertilizer, not high-nitrogen lawn fertilizer, because that will produce excess foliage and not many flowers.

From our Native Plant Image Gallery:

Sophora secundiflora