Why Fall Pruning Puts Your Trees at Risk
Canadian gardeners should avoid pruning trees during autumn months as this practice can significantly weaken trees throughout the harsh winter season. According to gardening expert Gerald Filipski, the optimal time for pruning is actually in spring, before buds begin to open.
The warning comes in response to a reader inquiry from Edmonton about maintaining three 35-year-old trees: an apple tree, a crabapple, and a flowering crab tree. While the reader had been pruning in fall based on older gardening literature, current expert advice strongly discourages this practice in Canadian climates.
Proper Pruning Timing for Healthy Trees
Spring emerges as the ideal season for major pruning work, according to Filipski's recommendations. For those concerned about controlling vigorous growth in apple and crabapple trees, a second light pruning in late summer (around August) can help maintain shape without compromising the tree's winter hardiness.
The reader had followed advice from an older Ortho Book for Growing Fruits & Berries in Western Canada, which suggested fall pruning would result in less vigorous growth. However, modern gardening wisdom for Canadian conditions indicates that fall pruning may leave trees vulnerable to winter damage and potentially prevent them from surviving the cold season.
Additional Gardening Concerns Addressed
Filipski also addressed another common gardening issue concerning red onions developing soft spots beneath dry, papery outer skins. Plant pathologist Dr. Leuan Evans identifies this condition as sour skin, caused by soil-inhabiting bacteria Burkholderia gladioli and B. cepacia.
Control measures include implementing a four-year crop rotation, avoiding overhead irrigation, limiting heavy nitrogen fertilization, and ensuring harvested onions are dried indoors as quickly as possible. These bacteria are typically introduced to Alberta gardens through onion sets and gladiolus bulbs.
Canadian gardeners seeking additional advice can access Filipski's weekly Growing Things Outdoors column online at edmontonjournal.com or through the epaper format at epaper.edmontonjournal.com. Questions can also be directed to filipskigerald@gmail.com.
