1Department of Horticulture, University of Georgia, Griffin Campus, 1109 Experiment Street, Griffin, GA 30223-1797;2 Department of Horticulture, University of Georgia, Coastal Plain Station, Tifton, GA 31793; 3Bamboo Farm and Coastal Gardens, 2 Cranebrake Road, Savannah, GA 31419
Seasonal, stem and leaf cold hardiness levels of male and female plants of Ilex purpurea Hassk. and Ilex rotunda var. microcarpa (Lindl. ex Paxton) were determined over two winter seasons. The samples for the cold hardiness studies were taken from established plants growing at the Univ. of Georgia Bamboo Farm and Coastal Gardens in Savannah. Each month, 40 stem cuttings (4 to 5 inches long) were sent by overnight mail for evaluation. The plants were prepared for laboratory freezing exposure tests within 2 h of receiving. The samples were visually evaluated after freezing exposure to estimate their cold hardiness. In general, Ilex purpurea was more cold-hardy than I. rotunda var. microcarpa over both seasons tested, except in midwinter (Jan. 1998 and Feb. 1999) where I. rotunda var. microcarpa was more cold-hardy than I. purpurea. Ilex purpurea attained cold hardiness earlier in the fall and lost its hardiness later in the spring. In general, few consistent differences were observed between the cold hardiness of male and female plants within species.