I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
The lilac probably need more sun. Also don't prune it after about early summer as it is setting bloom buds in mid to late summer for next spring. Any pruning should be done after it completes its bloom period.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
Q&A Library Searching Tips