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Apr 02, How to Prune Lilac Bushes. When pruning lilacs, cutting back the tops of overgrown stems is oftentimes not enough. It is generally better to cut the entire stem. Trimming lilacs is best accomplished using clippers. Remove spent blooms all the way to the stems to prevent seeding and encourage more blooms later on. Cut back about a third of the branches. Apr 27, Cut back 1/3 of the older lilac canes or branches. The following year cut out the next 1/3 of the oldest branches then the final year cut back the last of the oldest branches.

Doing this in 1/3’s will let you have blooms and still cut back the old worn out branches fully renovating the bushnotch.bars: Mar 14, University of Maine Cooperative Extension educator Marjorie Peronto demonstrates and discusses pruning techniques for your lilacs. Some people like a wide lilac bush while others prefer to keep their’s shorter and smaller in circumference. The rule of thumb, however, is to cut off each dead bloom and its INDIVIDUAL flower stem, which is referred to as “old wood”.

You’ll cut right above where the Estimated Reading Time: 7 mins. When lilacs are old and unproductive, it's time for a rejuvenative pruning. After flowering, cut out all dead, diseased and weak branches with lopping shears or a pruning saw. Cut out any branches.