Ask Burton: This week, a question involving common North Texas shrubs whose answer lies in understanding our soil and water. Q: I have purple loropetalum and ‘Sunshine’ ligustrum in a sunny, south-facing raised bed. They were planted early last year and did fine all summer. Now, the loropetalum is starting to show yellow leaves with green veins, and the ‘Sunshine’ ligustrum is losing tip leaves and the leaves that are there are stunted looking and tiny.

A: This is a problem of soil pH. Most of the soil in our area is high pH, as is the water supply provided by the North Texas Municipal Water District. This leads to occasional problems for acid-loving plants pulling specific metals and minerals out of the ground. If by some chance your bedding soil didn’t start out as high pH, our water supply will inevitably make it so. It’s only a question of time.

The ‘Sunshine’ ligustrum isn’t pulling copper from the ground properly, causing the tip leaves to stunt. The loropetalum isn’t pulling iron up properly, leading to the classic green vein, yellow tissue look you’re seeing now. Magnesium is an issue for many plants, for the exact same reason.

In our area, feed sulfur and sulfur-containing fertilizers to lower soil pH over time several times per year to plants which show these sorts of problems. Micronutrient supplements for specific plants are often helpful, but always start with the sulfur. There’s a good chance you have enough copper or iron from the fertilizers we normally recommend in the soil already. You just need to acidify the soil to let these plants use the metals properly.

And don’t worry too much about lowering soil pH too much if you live anywhere near the Covington’s Nursery. If you follow the label directions for soil sulfur (no more than one to two pounds per 100 sq. ft. of area, every few months), it’ll be hard to go wrong.