Hydrangea shrub (Hydrangea aborescens) growing in a garden. This deciduous plant produces flowers between early spring and late autumn, which are carried in bunches at the end of the stems. The flowers vary in colour depending upon the pH of the soil and the type of Hydrangea. The root of the hydrangea is used in herbal medicine as a diuretic (increases the production of urine) and a nephritic (reduces kidney inflammation).