What is considered late winter in Ontario for pruning Annabelle Hydrangeas?
Thank you for contacting Toronto Master Gardeners about your Hydrangea arborescens ‘Annabelle’. This type of hydrangea is a vigorous and reliable garden shrub. It forms beautiful hedges and with its giant white blooms, stands out in any garden.
Toronto Master Gardeners has a comprehensive Gardening Guide about all types of hydrangeas. You’re correct, Annabelle hydrangea should be pruned in late winter/early spring, taking care not to prune off buds that have formed on old wood if you’d like those flowers to develop. The structure of the plant is more visible during the dormant season, which allows you to make more effective cuts. Late winter would be around March in Toronto. A good rule of thumb is counting back 4-6 weeks from the average frost date, which is around May 4th in Toronto.
Below are a couple of previous answers from the Toronto Master Gardeners website that may be of interest, as well as an information sheet about this plant.
Sept 10, 2023