A common issue after stressful summer weather or other stress.... https://hortnews.extension.iastate.edu/faq/why-my-lilac-blooming-fall-instead-spring#:~:text=This%20out%2Dof%2Dseason%20bloom,%2C%20and%2For%20heavy%20pruning.

Here in Lexington my purple and my white French lilacs are in fragrant bloom. We had very warm then very chilly weather and they just burst out. They are setting tons of new leaves to replace the ones they always lose due to heat and drought and mildew. So pretty. I used to worry when they did this but they survive and thrive very nicely. Mother Nature knows more than I do I guess !!

the problem here is. heavy frost and or freeze is due in a few weeks ... there isnt time to releaf.. and if you do.. you would be wasting a lot of stored energy ...

and i doubt there is time to rebud for bloom next spring ...

the odds seem low.. that i will think about these lilacs late next may ... lol ...

ken

Maybe they are trying to cull them? Just a thought as mine are just fine...

Two of my large old lilacs are doing the same - blooming on sparsely leaved branches. I've never seen them do this.

Early part of this month, I noticed the green foliage had turned dark to black what seemed like overnight and then fell off. I couldn't imagined what had happened and thought the hedges were goners. Nope - some weeks later small green buds appeared, then clusters of leaves here and there, and then a single white bloom on one shrub and this morning I see probably four purple on the other.

I'm in NE Ohio.

My old old lilacs always look crummy. someone told me to cut them back to the ground to get new, better growth. Most of the branches have little or no growth, with a few blooms at the top. Sigh……..

debra

Need pictures!

"Most of the branches have little or no growth, with a few blooms at the top."

Do the "one third a year" rejuvenation pruning. Take out a third of it this year, another third the next, and you get the drill, lol.

Minus that they can be ugly monsters.