When the American industrialist and philanthropist, Pierre S. du Pont purchased a farm in Pennsylvania in 1906 to preserve its trees, he began creating the "horticultural showplace" that became Longwood Gardens. Du Pont personally directed the progress of Longwood through the 1930s, establishing its mission of "inspiring people through excellence in garden design, horticulture, education and the arts." The development of the blue billows hydrangea at Longwood in the 1960s, is one example of that philosophy.
Beginning in the 1950s, Longwood Gardens undertook a breeding program to develop new cultivars. To obtain the materials to create these cultivars, Longwood Gardens sponsored plant collecting expeditions, including one in 1966 to Cheju Island, the largest island in South Korea. The existence of Halla Mountain created a wide range of plant life on the island. Among the plants to catch the eye of expedition members was Caryopteris incana, a genus of flowering plants native to Asia, and the original source of the resulting cultivar, "Blue Billows."
Horticulturists, Richard W. Lighty and Edward G. Corbett discovered Caryopteris incana along a beach on Cheju Island. This species is characterized by its prostrate stems and dense, blue flower clusters. The species is one of more than 30 species and cultivars that Lighty has named and introduced to America. Caryopteris incana "blue billows" was designated as a Longwood Gardens cultivar at the conclusion of the 1966 Korean plant study tour.
In horticultural terms, the blue billows hydrangea is classified as a member of the Hydrangea serrata species and of the "lacecaps" variety. The delicate, lace-trimmed hats once worn by ladies of fashion were the inspiration for the term "lacecaps."
The blue billows hydrangea was selected as a Gold Medal Plant in 1990 by the Pennsylvania Horticultural Society. "Eye-appeal, performance and hardiness" are the criteria by which the society judges evaluate plants chosen to receive this award.
A variety of hydrangea hybrid named "Sweet Carol" was patented in 2004 in the United States (PP15239). It is the creation of Joseph Gray and was developed in Maryland and California. The parent plants are "Lanarth White," the mother plant, and "Blue Billows," the father plant. This variety is one of the more than 120 varieties of hydrangeas.
The blue billows hydrangea is included in horticultural reference books such as "Dirr's Hardy Trees and Shrubs: An Illustrated Encyclopedia" by Michael A. Dirr, 1997; "Hydrangeas For American Gardens" by Michael A. Dirr and Bonnie L. Dirr, 2004; and "Encyclopedia of Hydrangeas" by C.J. van Gelderen and D.M. van Gelderen, 2004. A useful general reference book is "Hydrangeas: Species and Cultivars," published in 1992, by Corinne Mallet, the French breeder of hydrangeas and an expert on the subject.