Five evergreen rhododendron cultivars were compared for flower bud cold hardiness in laboratory freezing studies on 6 dates. ‘Roseum Elegans’, ‘Catawbiense Boursalt’ and ‘Boule de Neige’ were more cold hardy on most sampling dates than ‘America’ and ‘Lee’s Dark Purple’. The relative cold hardiness of these 5 cultivars was consistent on several winter dates over several years. Injured florets were black and readily separated from uninjured white florets upon dissection of the inflorescence bud after freezing.
Received tor publication March 16, 1981. Vermont Agriculture Experiment Station Journal Article No. 471.
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Partially funded by a grant from the Vermont Plantsmen’s Association.
Associate Professor and former Research Technologist, respectively.