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Sunday - March 30, 2008

From: SAN ANTONIO, TX
Region: Southwest
Topic: Pruning, Soils, Shrubs
Title: Non-blooming Texas Mountain Laurel
Answered by: Barbara Medford

QUESTION:

Two questions: 1. My mountain laurel (10 yrs old) has never had blooms. Is this a gender plant issue? 2. I have been seeking a groundcover that grows in shade and will take foot (dog) traffic. Ideas?

ANSWER:

All the information we can find on Sophora secundiflora (Texas mountain-laurel) says that it is a very slow grower and a "problematic" bloomer. First of all, it is not a gender issue. The flowers of the mountain laurel are hermaphrodite, having both male and female flowers, and are pollinated by insects. The flowers attract both butterflies and bees, so you wouldn't think the problem would be a shortage of pollinators, but you have to have flowers to pollinate! So, let's look at the cultural practices. At ten years, if the plant itself is prospering, it should be blooming, problematic or not. Although a lot of the information says it will grow in part shade, it will definitely bloom better if it is in full sun. Obviously, with a plant that size, you're not going to be moving it into a sunnier spot, but perhaps there are shrubs or trees around it that could be trimmed back to provide more sunlight. Second, don't fertilize it, especially not with nitrogen-high fertilizer, such as lawn fertilizers. The plant is a legume, and has an internal mechanism that permits it to fix nitrogen in the soil, some of which it uses itself, and some of which can be used by other plants. Many plants are adversely affected in terms of blooms when they are over-treated with nitrogen. Yet another suggestion is that it be pruned. Your plant is already past the bloom period in this part of the country. The mountain laurel produces flowers only on one-year-old wood. Pruning now, getting out weak branches, trimming off long, thin stems, and general cleanup should propel it into blooming on that new wood that will sprout after the trimming. And, remember, when you DO get blooms (as we hope you will) the seeds are extremely poisonous and should be kept from access by children and pets.

On your second question, we have three suggestions for low-growing groundcover that will grow in part shade. Remember, even very sturdy, invasive non-native lawngrasses like St. Augusting and Bermuda can get trails beaten into them by dogs making their persistent rounds, but if the dog is just crossing the area now and again, these should all be fine.

Phyla nodiflora (turkey tangle fogfruit)

Dichondra argentea (silver ponysfoot)

Hydrocotyle bonariensis (largeleaf pennywort)

Sophora secundiflora

Phyla nodiflora

Dichondra argentea