Ask Mr. Smarty Plants

The oak-leaf hydrangea will perhaps grow in Comal County, but I doubt that it will thrive.

To Find out its growing conditions, you can read about the oak-leaf hydrangea (Hydrangea quercifolia) in the Native Plants Database on the Wildflower Center web page. At the top of the information page about the oak-leaf hydrangea is a menu bar listing several choices: Taxonomy, Benefits, Bloom, Growing Conditions, etc. If you choose Growing Conditions, you can see various conditions for its growth including the moisture and soil pH preferred by the plant. Oak-leaf hydrangea likes a moist soil and a pH of about 6.7-7.2. The pH of most of the soils in Comal County are in the 7.4-8.4 range. There are locations in Comal County where soils have lower pH values, however. You can learn the soil pH for your particular location by determining its soil type from the maps in the Comal and Hays County Soil Survey produced by the USDA/Natural Resources Conservation Service (NRCS) office. The public library in New Braunfels is likely to have a copy or you can order one free of charge from the NRCS office in Temple, Texas (254-742-9800). The soil pH and the soil moisture requirement could be the limiting factor for growing it successfully in Comal County.

You can also read about the oak-leaf hydrangea in the USDA Plants Database.