An older lilac may stop blooming if neighboring trees have grown up.

Jul 08, There are two approaches you can take. The less drastic approach to getting an overgrown lilac back into shape is to use the third rule. Prune a third of the oldest branches all the way to the ground each year for three consecutive years. 1  Start by taking out the thickest stems first.

Apr 02, Most lilacs don’t require pruning until they reach about 6 to 8 feet ( m.) tall. The best time for pruning lilac bushes is right after their flowering has ceased. This allows new shoots plenty of time to develop the next season of blooms.

Pruning lilacs too late can kill young developing buds. If you are pruning lilac trees or shrubs entirely to within inches of the ground, it is best to do so in early spring. 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 fallif absolutely required. Click to see full answer. Correspondingly, when can you cut back lilac bushes? Nov 18, The best time -- and only correct time, really -- to prune lilacs is just after blooming.

All shrubs fall into one of two categories; some, like many of the hydrangeas, bloom exclusively on proper tree pruning practices wood and can be pruned to the ground each fall if required. Others, such as lilacs, bloom only on old wood from the previous season. Thus, if you prune at any time other than immediately after flowering, you will cut off next year's treegrinding.barted Reading Time: 2 mins.

The best time - and only correct time, really - to prune lilacs is just after blooming. 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 required.