Mountain hydrangeas (Hydrangea serrata) are woody, deciduous shrubs offering year-round interest. Although some cultivars produce mopheads, they typically bloom in delicate lacecap inflorescences early summer to fall. The flattened flower clusters have an outer ring of sterile, papery florets surrounding a center of fertile, star-like florets. The flower clusters change color with the pH of the soil, turning pink in alkaline soil and blue in acid soil. Long-lasting, the flowers make excellent cuts for arrangements, fresh or dried. A valuable food source, the florets feed butterflies and beneficial insects in summer, and the seeds sustain songbirds in late fall. After the first frost, the clusters turn a tan to caramel color but remain attractive. On mature plants, shredding and peeling papery brown bark reveals glimpses of the underlying cinnamon hue on stems and branches, adding a textural element to the winter garden, especially pleasing against a snowy backdrop. The hollow stems also provide nesting habitats for bees.
Indigenous to mountain woodlands, mountain hydrangeas add a natural effect to the landscape. The shrubs have a medium growth rate and a rounded habit of serrate dark green leaves on long, slender stems. Similar to big leaf hydrangea (H. macrophylla), mountain hydrangeas tend to be smaller and more compact, their leaves slightly narrower. Less formal, mountain hydrangeas have a wilder look and are considerably hardier.
Easy to grow and maintain, mountain hydrangeas prefer some morning sun and afternoon shade; rich, moist, well-drained soil; and plenty of water. They can tolerate more sun if the soil is kept consistently moist. Some varieties bloom on new wood, some on old wood, but for best overall blooming, avoid pruning and protect plants on spring nights when frost or a freeze is expected.
