I’m very dubious that you're seeing flower buds in August. I suspect you're seeing seed pods. I can see some.

Prune right after flowering in spring. Cut out any dead wood and shape the tree as you wish.

Floral - excellent info, thank you! Seed pods make sense. I don’t really know what I’m looking at LOL

Callirhoe - can it handle an aggressive haircut all around? Am I better to do it in stages like some of the rejuvenation prune instructions for shrubs?

If you want it to remain single trunked and not start producing a lot of suckering canes (as is most common with lilacs), then trim back lightly.

I honestly do not see much of any concern with this lilac. They are not at the best of times very dense shrubs. Personally, I'd just remove any dead wood and call it good.

Except for deadwood removal, it doesn't require pruning. Your choice. Depends on what your after. Do you dislike its current shape?

agree ... once you heavily prune it .... it will sucker no end.. and then you will end up with a shrub ... that will take over the yard in a few years ...

the lawn is in drought.. which means the tree is.. and that is probably why its not looking its best ... it probably needs along deep slow drink ...

if it were mine.. id put a small water ring on it ... at low pressure.. so it makes a 3 foot ring or so of water .... and let it run for many hours ... moving it every hour or so ... this is in my price range:

https://www.walmart.com/ip/METAL-CIRCULAR-SPOT-SPRINKLER/180506960

i would also fert the lawn in fall.. when it comes out of dormancy .... with a cheap balanced garden fert ... like 12-12-12 .. or 16 cubed ... and the lilac will get more than it needs ...

and i bet it looks a lot better next spring...

and do properly prune out all dead stuff ... leave no stubs ... ask if you dont know what that means ... dead stuff is always removed.... and as its dead.. it doesnt matter when ...

ken

ps: can you believe i recommended fert.. lol ..