Hydrangea macrophylla
The large blooms of these petite, woody perennials bring splashes of cool color in shades influenced by soil acidity. Gardner Museum horticulturists grow bigleaf hydrangeas in both the lacecap and bonnet forms. Hydrangeas enjoy a cold dormancy outdoors during winter. In February and March, the plants are moved into the warmth of the greenhouses which coaxes them into earlier blooms.