Q.beautiful Japanese lilac
I have a beautiful Japanese lilac. Do I have to cut the dead flowers after they are done blooming? My tree is very healthy. Last year I hardly got any blooms on it. Was wondering if it was because I didn’t trim the dead flowers. However, this year I have lots of blooms on it.
Yes you can prune off the spent blossoms as needed.
Usually pruning can be done after the the plant is done blooming so if you don't dead head, this would take care of the old flowers.
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/japanese-lilac-information.htm