Time of Pruning Effects on Cold Hardiness of Butterfly Bush

Buddleia davidii 'Royal Red' (butterfly bush) is a woody shrub with rich purple, fragrant flowers in long panicles known to attract butterflies and bees. Butterfly bush grows as an arching shrub and blooms on new wood and is used in perennial borders, butterfly gardens or in mass shrub plantings. This shrub grows profusely throughout the summer and can become unkempt late in the season in the landscape. Growers also find it necessary to prune butterfly bush throughout the growing season to maintain compactness for shipping, as a source of cuttings or to save valuable space for overwintering.

This study was conducted at Auburn University to determine how time of pruning affects cold hardiness in Buddleia davidii 'Royal Red'. The results of the study demonstrate that pruning buddleia before the plants have become fully dormant in the Fall increases the chance for winter injury resulting in death. Growers and homeowners alike should prune late in winter or early spring to decrease the chance of cold injury.

(from a student research paper presented at SNA 2002 by Jennifer Warr, Gary Keever, Doug Findley, and Raymond Kessler, Auburn University, Department of Horticulture).

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North Carolina State University