Yes, but it is better to trim the old blooms as soon as.
Begin by pruning dead or diseased stems , pencil-thin suckers, and twiggy growth.
Apr 28, To prune your lilacs, start deadheading in early-to-late spring by cutting the flowers at their base just after they’ve reached their peak. You should also cut any flowers that are already dying so they don’t sap energy that could be used for new growth%(4). Jun 03, Pruning lilacs is best done within a few weeks after the blooms fade. Trim them with bypass pruning shears, cutting blooms off just above the place the stem forks beneath the bloom. Old growth should also be cut back every few years to help keep the bush Estimated Reading Time: 5 mins.