Leaves and stems of four selections of Raphiolepis umbellata Makino were evaluated for cold hardiness at various times throughout the winter over a two year period and compared to the hardiness of their cold hardy parent plant (PI 277653). All four selections were equally or more cold tolerant than the parent plant on all test dates over both years tested. The leaves of these plants were hardier than the stem tips, but were similar to the cold hardiness of two year old stems. During midwinter the leaf and two year old stem cold hardiness ranged from −15 to −18°C (5 to 0°F). These data indicate that the new selections have good cold hardiness potential and may increase the range of adaptability of raphiolepis.
The research reported here was supported, in part, by a grant from the Horticultural Research Institute, Inc., 1250 I Street, N.W., Suite 50, Washington, DC 20005. The authors thank Glen Kent, Sherrie Stevens, Malgorzata Florkowska, and Evelyn Weatherly for their part in making this manuscript possible.
3Wildflower Project Coordinator.