Most shrubs are pruned on the homeowner’s calendar rather than the plant’s, which is why so many hydrangeas and lilacs never flower. Anything that blooms on old wood sets next year’s buds within weeks of finishing this year’s flowers — prune it in early spring and you have just cut the flowers off. We prune by species and season, and where the right month has passed we will say so and book you for it rather than take the money now.