By Jeff Floyd
Certified horticulturist and arborist
When it comes to evergreen shrubs in the landscape, few can brag about having brilliant color, wide temperature hardiness, and the ability to thrive in almost any soil type. Texas sage (Leucophyllum frutescens) checks all the boxes. It is found growing freely along the upper Rio Grande valley of northern Mexico and Texas, becoming almost invasive in some locations. But can it really predict rain?
Also known as barometer bush because of its seeming ability to predict rain. Texas sage is sensitive to changes in humidity, so even watering the soil around it can cause blooms to increase. Indeed, it often sends out a profusion of lavender blooms a few days before rain. However, sometimes the blooms show up after it rains. So what is going on?
Low-pressure systems mean the air is light allowing it to rise and build up clouds and moisture. This causes humidity to increase. As water vapor in the surrounding air goes up, plants tend to lose less water from their leaves. In the case of Texas sage, this means more water is available in the plant to produce flowers. Whether the barometer bush will bloom before or after rain may depend on several factors.
For example, it takes a few days for moisture to increase within this drought-tolerant native. If a low-pressure system develops rapidly, the plant may not have enough time to store enough water and flowers before the rain. In this case, flowers could turn up a few days later. Even if it doesn’t rain, Texas sage will still produce blooms once it has stored enough water to trigger bud development.
Texas sage is not a true sage. The flowers of this official state native shrub of Texas have the same shape as culinary and ornamental sages with two upper petals and three lower petals converging to form a tubular structure. It’s the perfect shape and purplish color for attracting Texas pollinator insects.
If you are interested in finding a spot for Texas sage in your garden, don’t hesitate, but plant it in areas that drain well. It doesn’t respond well to consistently wet roots. There are several varieties ranging from the popular three-foot by three-foot ‘compact’ with silvery foliage to the six-foot tall and six-foot wide ‘green cloud’ which has bragging rights to longer bloom periods surrounded by dark green foliage.
