Pruning Lilac Bushes

Question

How late can lilac bushes be trimmed in Zone 5

Answer 1

Lilacs should not be pruned past mid-summer. You can inspect the ends of the branches and you can see where the new buds are developing. If you only want to trim off the seeds or dead flowers, you can do that without cutting into the new buds.

If you want to remove the oldest canes to make way for new canes, you can still do that. Only remove a couple down to the base.

https://www.gardeningknowhow.com/ornamental/shrubs/lilac/pruning-lilac-bushes-when-to-trim-lilac-bushes.htm

https://hortnews.extension.iastate.edu/1993/2-10-1993/lilac.html