The nursery industry continues to develop improved methods for successfully overwintering container-grown nursery stock. Experiments were conducted using several different species of woody ornamentals ranging from species known to be cold hardy to cold tender. Eighteen species were subjected to temperatures ranging from 20F to -20F and observed for post-stress performance and viability. Rates and timing of acclimation, mid-winter hardiness, and deacclimation of seven species were determined by examining the shoots for injury after subjecting them to controlled freezer conditions. The roots of the same seven species were exposed to three different overwintering systems: in a polyhouse, pot-to-pot above the ground, and pot-in-pot below the ground. Cold hardiness of root and shoot systems and the effects of warming temperatures on shoots were determined as well as the post-stress performance of each species. Results of this research will be presented.
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