I was just curious as to why wisterias are blooming like crazy all over Toronto this year? Most years there are not nearly as many blooms.
Bloom quantity can be influenced by many factors but it mostly influenced by environmental conditions. Last year (Spring 2016) many trees and shrubs had relatively few blooms, likely influenced by cold snaps occurring during the development of blooms. When this happens, the energy that would have been put into bloom production is stored in the plant roots. True to patter, this spring (Spring 2017) saw a plethora of blooms on those plants that hardly produced any in 2016.