I guess I was a bit surprised to find this hydrangea in a book on medicinal herbs. The species, as opposed to 'Annabelle', has smaller blooms but still is lovely. In its native range, from New York south to Florida and west to Missouri, it can be found growing in moist, rich woodlands, and I find that here in our zone 6ish garden it grows best in light shade where it gets sufficient moisture. I also have one growing at the base of a large mulberry tree where it gets much less moisture unless I remember to throw a 5 gallon bucket of water on it, and though it grows well, it is not nearly as large, nor are the flowers as large, as the one in better, moister soil.
The part of the plant that is used medicinally is the root, which has variously colored layers of root bark that can be peeled back, one layer at a time, and which gives it the sometimes used name of seven-bark. When a fresh root is dug, it is cut or crushed to be used in an unfusion, 1 teaspoon of root to a cup of boiling water, taken a mouthful at a time throughout the day. Although the book says that it was known that it wouldn't get rid of gall stones, it was taken to get rid of 'gravelly deposits'. It was also know to the Cherokee tribe for that purpose. It was thought that it would assist in removing brick dust deposits from the bladder and so was a popular remedy in areas with brick factories.
Even if you have no need or desire to use this shrub medicinally, it is still well worth growing for its beauth and ease of cultivation. It doesn't seem to have pest problems, doesn't mind a little drought, though in very dry spells it would like a drink every couple of days. Expect it to get about 4 feet tall and maybe 6 feet wide in time.