Why don’t my lilacs bloom? They were planted 4-5 years ago and they get plenty of sun. The shrubs are 4-6’ tall, the foliage is healthy, but there are no flowers. Please help.
Stubborn lilacs may refuse to bloom for a couple reasons. First off, a healthy, fast-growing lilac may have received too much fertilizer which is causing the plant to develop vegetatively rather than reproductively. In this case, reducing the amount of fertilization will help slow the growth. Sometimes inducing a small amount of stress may cause the plant to set flower buds. This can be accomplished with careful pruning or by withholding moisture during dry periods. Never let a plant go completely dry to the crispy stage, but a slight hint of wilt during the summer may just be the right incentive for enjoying blooms next spring.
The second reason for lilacs not blooming may be due to improper pruning. Flower buds begin developing during the summer as soon as the new growth begins to harden. Any pruning done from that time forward may remove the terminal buds containing the flowers. Remember, the best time to trim a lilac is just after flowering – that is, once yours begins to flower!