CONTAINER TYPE AND WINTER TREATMENT MODIFY ROOT ZONE TEMPERATURES AND GROWTH OF HARDY SHRUBS
Cornus sericea Baileyi and Viburnum plicatum tomentosum Mariesii were grown in no. 10 plastic or equivalent fabric containers in USDA zone 5b for two years. Winter treatments included stacking and covering (as control) versus leaving plants in situ, either unprotected or with insulating pot covers for winter protection. Minimum root zone temperatures (RZT) were 2-3°C higher in fabric pots during cold events. Plant response was associated with duration of RZT below lethal cold thresholds for mature roots but not young roots, evidence that young roots are not critical to survival and recovery of plants in the spring. Pot covers improved survival and plant quality, which by late spring was comparable to traditional overwintering methods. Treatment differences were more pronounced for Viburnum, which demonstrated less root cold tolerance than Cornus. Viburnum survival rate was greater in fabric than plastic for unprotected plants and plants in fabric containers had better root and shoot ratings than plants in plastic containers after two winters. This study demonstrates the potential for modifying overwintering practices for nursery stock if the root cold tolerance of each species is considered.
Neal, C.A. (2013). CONTAINER TYPE AND WINTER TREATMENT MODIFY ROOT ZONE TEMPERATURES AND GROWTH OF HARDY SHRUBS. Acta Hortic. 990, 113-120
nursery, woody plants, overwintering, Viburnum plicatum tomentosum, Cornus sericea