I have to agree with trimming off the spent flowers because the new growth supplies the blooms for the next year. However, I went nuts on my lilac bushes that divide my back yard from my field a couple years ago because they were so overgrown and thick they barely flowered. This year I had the most blooms in 5 years!
By
06/20/2009
One of the widows on our street where we used to live, asked my husband if he would prune her lilac bush.
In the autumn when the growing season ended he just sawed off a lot of the limbs.
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My lilac bushes do not have too many flowers this year. When is the proper time to prune? Perhaps I trimmed too much last year. I try to keep them from growing too large and out of control.
Hardiness Zone: 6a
Rose from Malvern, PA
RE: When to Prune Lilac Bush
You are suppose to cut right it after bloom dies, because they flower on the new growth. (05/13/2008)
By Bonnie
RE: When to Prune Lilac Bush
It is my experience that lilac bushes tend to bloom in cycles, every second year (in my climate) you get loads of blossoms. The alternate year, very few. Be sure to cut off the spent blossoms after they die, especially when you are not going to do a massive pruning job. (05/14/2008)