My Lilac is not doing well. I planted it seven years ago, and it started quite healthy and finally bloomed beautifully in five years. But since then, it stopped growing and had spider webs on the branches. It does not look healthy. After it bloomed in five years, it has only bloomed once and only bloomed partly. I noticed some of the branches were dead, so I cut them off. I don’t know what to do to make it healthy or how to.
The Gardener’s Answer
All plants are happiest when they are given optimal growing conditions. Each plant has its own specific requirements, and Lilacs (Syringa) prefer to grow in fertile, well-drained soil with at least six hours of sunlight each day. Good air circulation is important for Lilacs. Depending on the species/cultivar that you are growing, some are more disease resistant than others. Lilacs can be susceptible to several different insect and disease issues especially if they are not happy with their growing conditions.
You can take a sample to your Cooperative Extension Service or to a reputable garden center for a proper diagnosis. The lack of blooms can be due to insufficient nutrients and/or sunlight, but flower buds can also be damaged by spring frosts.
If necessary, Lilacs should be pruned shortly after they have finished blooming or anytime you notice a dead, diseased, or crossing branch. Older Lilacs may also benefit form having one-third of their oldest branches pruned back to the ground. This will help rejuvenate the plant and encourage new growth. For now, clean up all debris around the plant and add 2-3 inches of mulch around the base of the plant to help protect during the winter months.