Influence of Winter Protection Covers on Survival and Hardiness of Container Grown Ilex crenata Thunb. ‘Green Island’ and Euonymus fortunei (Turcz.) ‘Emerald 'n Gold’

Abstract Five systems for protection of container grown nursery stock were compared for freeze injury to shoots and roots of Ilex crenata Thunb. ‘Green Island’ and Euonymus fortunei (Turcz.) ‘Emerald 'n Gold’. In three treatments, plants were protected starting November 15, 1988 either in a white co-polymer house or with structureless non-woven polypropylene covers (N-Sulate™ or Typar™). In a fourth treatment, structureless clear polyethylene was applied when temperatures were cold enough (−7°C (25°F) to cause injury. The controls were not covered. The white co-polymer house and the temporary covering with clear polyethylene reduced the number of hours below −7°C (25°F) in the canopy or medium and resulted in fewer plant losses compared to the nonwoven covers or the controls. Development of shoot and root hardiness of both species was monitored prior to and after the low temperature period. Roots of plants under long-term protective covers were slightly less hardy than those not covered.