The flowering performance of 21 Hydrangea macrophylla cultivars was evaluated for three years at two locations. Ten plants of each cultivar were planted during 1997 in field plots at McMinnville, TN (USDA hardiness Zone 6b), and New Franklin, MO (USDA hardiness Zone 5b). The number of inflorescences was recorded every two weeks from May through September in 1999, 2000 and 2001. Daily maximum and minimum temperatures were recorded from October 1998 through September 2001. Differences among cultivars were found all three years at McMinnville and in 1999 and 2000 in New Franklin. While rankings of cultivars for number of inflorescences differed among years and locations, ‘All Summer Beauty’ and ‘Nikko Blue’ were consistently among the best performing cultivars. ‘Blauer Prinz’, ‘Blue Wave’, ‘Mariesii’ and ‘Todi’ flowered poorly all 3 years at both locations. No cultivar flowered reliably all three years of the study. Although some cultivars flowered sporadically throughout the summer, no remontant cultivars were identified. Poor flowering performance during the study appeared to be related to damage to aboveground portions of plants from a combination of early fall freezes, low winter temperatures and late spring freezes.

This content is only available as a PDF.

Author notes

This research was funded in part by a grant from The Horticulture Research Institute, 1000 Vermont Avenue, NW, Suite 300, Washington, DC 20005. The assistance of John Shopland, Superintendent, and staff of the University of Missouri Horticulture and Agroforestry Research Center is gratefully acknowledged.

2Research Geneticist.