The parents of this lovely Lacecap variety were found growing on the wooded slope of a Korean mountain, which explains its exceptional hardiness. It produces delicate clusters of light blue flowers that last for several weeks in early to midsummer (July here in Connecticut), turning a stunning deep crimson as they age. Fall foliage is an attractive shade of burgundy. Excellent in a shady border with Ferns and Astilbes such as 'Visions.' 'Blue Billow' is a reliable bloomer through Zone 6, and adventurous gardeners in Zone 5, where flowering occurs 3 or 4 years out of 5 may also wish to give it a try. It also performs well at our nursery in full sun. Blooms on old wood.
Hydrangea is a valuable genus of some 100 species of shrubs and vines grown for their large and very showy flower heads. Hydrangeas are at their best in summer and fall—a quiet time for most woody plants—and are worth having for that reason alone. For more information on Hydrangea care, click Growing Guide.