|My lilac trees are several years old and have never produced flowers. Why?
|The two most common reasons lilacs fail to bloom are lack of sunlight (these shrubs prefer full sun all day long) and pruning at the wrong time of year. They should only be pruned right after they bloom (ie late spring) because they bloom on old wood, meaning wood that grew the previous year. If you prune in late summer or fall or very early spring, you will cut off the flower blossoms.