Q.Why Won’t My Lilac Bush Bloom?
I have a 9-year-old lilac that has never bloomed. It looks in good health, but every year when it gets buds, they never develop into blossoms. We have frosty weather in the spring but everyone around me has blooming lilacs. I have noticed the little bud leaves turn brown and fall off.
Certified GKH Gardening Expert
This article should help with that: https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm