Ask Mr. Smarty Plants

This particular member of the Mr. Smarty Plants team may very well have been the one who told you that, as I was visiting with attendees of the Wildflower Center Garden Tour. That garden had a beautiful (small) planting of Hydrangea quercifolia (Oakleaf hydrangea). We fielded many questions from attendees wanting to know if they could grow those here, or other varieties or even non-native varieties. Frankly, that gardener had no doubt done a number of things, including adding a lot of leaf-mold compost, to increase the acidity of that soil. Hydrangeas are very much a soil-dependant plant, and they tend to be native to areas where the leaves from deciduous trees and pine needles have fallen on the ground and slowly decayed for many centuries, contributing to an acid soil. As you can see from this USDA Plant Profile map, oakleaf hydrangea is not even native to Texas at all, although they do grow well introduced into East Texas. Follow the plant link above to read all about this plant, including these two lines:

"Soil Description: Moist, fertile, well-drained soils.
Conditions Comments: Susceptible to sunscald, chlorosis in alkaline soils, and winter dieback."

Our Native Plant Database has two other hydrangeas native to North America, Decumaria barbara (Decumaria) (not a true hydrangea but a member of the same family), which grows natively in the same areas as oakleaf hydrangea; the other is Hydrangea arborescens (Wild hydrangea), which grows to the north and east of Texas, but not in Texas, itself.

We know that a number of hydrangeas are sold by nurseries, most of which, we are sure, are non-natives or extensively hybridized, so we have no information on them in our Native Plant Database. Because we can't help you with those, here are two articles we found that might be of use. Remember,  most of those named are hybrids or non-natives.

Planting and Transplanting Hydrangeas

All About Hydrangeas