Ask Mr. Smarty Plants

"Pride of Houston" is a trade name for Ilex vomitoria (yaupon). It may have been bred from selections that did better in the more acidic, sandy soils of East Texas. This USDA Plant Profile map does not show yaupon growing in Tarrant County. That doesn't mean it won't, it just means it is not native to that part of the state. We are guessing that the yellowing leaves are the results of chlorosis, which is the yellowing of leaf tissue due to a lack of chlorophyll. Possible causes include poor drainage, damaged roots, compacted roots, high alkalinity and nutrient deficiencies in the plant. The best way to remedy this problem is in improving the drainage around the roots and making the soil nutrients more available to the roots. The soil in Ft. Worth is pretty alkaline, and amending the soil with compost or some other organic material is the best way to unlock those nutrients. You can begin by working as much compost as possible into the soil around the yaupon, and continuing to add compost periodically. Use either the compost or a shredded hardwood mulch to mulch the root area. As this decomposes, it will continue to improve the soil texture, and permit the roots to access the trace elements, especially iron, that they need to get back the green in the leaves. You didn't say what the light exposure on your plants is, but the yaupon does best in part shade, which we consider to be 2 to 6 hours of sun a day. The amount of light a plant is getting can also affect leaf color.

Ilex vomitoria

Ilex vomitoria

Ilex vomitoria