Seasonal Cold Hardiness Differences of Three Woody Plant Taxa during the Production Stage and as Established Landscape Plants

Abstract

Abstract Seasonal cold hardiness levels of Crape myrtle (Lagerstroemia L. ‘Natchez’), Leyland cypress [× Cupressocyparis leylandii (A.B. Jacks. and Dallim.) Dallim. and A.B. Jacks.] ‘Haggerston Gray’ and Lacebark elm (Ulmus parvifolia Jacq. Allee™) were determined for nursery production and established landscape plants grown at the same location. Differences in cold hardiness between the growth treatments were taxon specific. During October, November and December, nursery-grown crape myrtle plants were up to 11°C (20°F) less cold hardy than those established in the landscape. Differences in Leyland cypress cold hardiness were detected, but were not as great as in crape myrtle. During October, November and December newly transplanted Leyland cypresses were from 3 to 6°C (5 to 11°F) less cold hardy compared to established landscape plants. Differences occurred between nursery production and established landscape plants of lacebark elm in January and February.