Troubleshooting
Madame Lemoine Lilac problems — and how to fix them
Madame Lemoine Lilac (Syringa vulgaris 'Madame Lemoine') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
Common white coating on leaves in late summer, especially in dry years with poor air circulation; improve spacing and avoid overhead watering. Rarely fatal.
Failure to flower
Most often caused by incorrect pruning (removing flower buds on old wood) or insufficient chilling hours in mild winters; avoid pruning except immediately after flowering.
Lilac borer
Sawdust-like frass at stem bases indicates lilac borer larvae; prune and destroy affected stems and maintain plant vigour.
Verticillium wilt
Sudden wilting and die-back of branches; remove affected wood and avoid replanting Syringa in the same soil.
Suckers
Strong suckers from the rootstock (if grafted) will overtake the cultivar; remove them at their point of origin below soil level promptly.
Prevent madame lemoine lilac problems before they start
Most madame lemoine lilac issues are care-mismatch, not bad luck. Dial in the basics:
Madame Lemoine Lilac problems — FAQ
Why is my madame lemoine lilac powdery mildew?
Common white coating on leaves in late summer, especially in dry years with poor air circulation; improve spacing and avoid overhead watering. Rarely fatal.
Why is my madame lemoine lilac failure to flower?
Most often caused by incorrect pruning (removing flower buds on old wood) or insufficient chilling hours in mild winters; avoid pruning except immediately after flowering.
Why is my madame lemoine lilac lilac borer?
Sawdust-like frass at stem bases indicates lilac borer larvae; prune and destroy affected stems and maintain plant vigour.
Why is my madame lemoine lilac verticillium wilt?
Sudden wilting and die-back of branches; remove affected wood and avoid replanting Syringa in the same soil.
Why is my madame lemoine lilac suckers?
Strong suckers from the rootstock (if grafted) will overtake the cultivar; remove them at their point of origin below soil level promptly.