Answer: Lilacs bloom better after a pronounced winter chill which sometimes explains why they bloom better one year than the next. But, lilacs also spend the summer months developing flower buds for the next spring's floral display. If these buds begin to open and then experience a late spring frost, the buds can die and you will get no flowers. Lilacs don't really need to be fed - they get what they need from the soil, but you can prune your lilac back now to encourage new growth. The plant will still have time to develop flower buds later this summer. I'd prune it back by several inches (and up to one third). Your lilac will respond to pruning by producing lots of new (flowering) stems which will help it maintain a full and bushy look and provide lots of places for flowers. Best wishes with your lilac.
Q&A Library Searching Tips