I'm dealing with very old over gown lilacs that likely never have been pruned in any manner. How far do I cut these back and when do I cut these back and how long after I cut these back will the shrubs flower again
Hennepin County Minnesota pruning lilacs
Lilacs should be pruned within a week or two of when they bloomed. If they are pruned later than that the new flower buds will be cut off. Lilacs can be renewal pruned and cut off at the ground but it may be many years before they bloom again, 1-8 years. It is variable and difficult to predict.