My lilacs are barely flowering
My common lilacs are around 6 years old now. Some came from cuttings, others from seed. They used to put out a lot of flowers but for the last couple of years, they hardly put any out at all.
Some of them are going crazy making suckers (more than I can compete with) and others aren't making many suckers but the lack of flowers is universal amongst all the plants.
Some get full sun while others get part sun. None get fertilized and I haven't pruned them besides the suckers.
For the last couple of winters, it's been very mild. I'm in zone 7a but we hardly got any snow or very cold temps.
I used to have lilacs at my old house and we never pruned them, never fertilized them and they were in part sun and they always put out masses of flowers.