Lilacs are a beautiful, fragrant sign of spring, and they usually bloom vigorously for weeks. Why, then, do they sometimes refuse to flower? Here are the most common reasons lilacs don't bloom, and what you can do about it:
Not enough sun. Lilacs need at least six hours of direct sun each day to bloom well.
Damaged by critters. Protect lilacs from animal damage in winter by placing wire fencing around them in fall. Damaged shrubs may struggle to bloom.
Not enough water. Keep lilacs watered during dry weather, and add 2 to 3 inches of mulch to conserve moisture and deter weeds.
Pruned at the wrong time. Prune lilacs immediately after they finish flowering in the spring if you prune them later, you¹ll remove the next season¹s flower buds.
Too much fertilizer. Excess nitrogen can promote growth of leaves at the expense of flowers. Lightly fertilize lilacs with a balanced fertilizer every two to four years.
Newly planted. Common lilacs (Syringa vulgaris) may take five or more years to bloom, and other species and cultivars take one to two years.