Of course, you can prune in the fall if absolutely required. One may also ask, when should lilac bushes be trimmed? The time to prune mature lilac plants is just after the flowers have faded in the spring. Lilacs set next season's flower buds almost immediately, so late pruning will mean sacrificing the next year's flowers. Jul 08, When to Prune Lilac Bushes. Many of the newer lilac varieties grow quickly and might need pruning starting in their second or third year.
In general, by the time a stem reaches more than 2 inches in diameter, it should be pruned. If you are diligent with annual pruning of your lilac, the shrub will grow to about 8 feet tall with flowers. Nov 17, For lilacs, the recommended method is generally to remove one third of the old wood each year immediately after flowering and shape the shrub over a number of seasons. Of course, you can prune in the fall if absolutely bushtrim.buzzted Reading Time: 2 mins.
One possibility- lilacs flower on the growth that occurs after the last flowering- so if you prune in the fall, you’ll be pruning off the branches that would otherwise flower the next spring.