Troubleshooting
Tansy problems — and how to fix them
Tansy (Tanacetum vulgare) 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.
Invasive spreading
Vigorous rhizomes form dense colonies and it self-seeds freely; it is a listed noxious weed in some US states. Plant with a root barrier or in a contained bed and deadhead before seed set.
Flopping in rich soil
Tall stems sprawl in fertile ground or shade; grow hard in lean soil and full sun, or cut back by half in early summer for sturdier regrowth.
Aphid infestation
Aphids cluster on soft new shoots and flower stems; tolerate minor numbers (tansy attracts beneficials) or dislodge with a water jet.
Powdery mildew
White coating develops on foliage in crowded, humid conditions; thin clumps and improve airflow to prevent it.
Prevent tansy problems before they start
Most tansy issues are care-mismatch, not bad luck. Dial in the basics:
Looking for tansy in general rather than its problems? Read the full tansy care guide — light, water, soil and feeding.
Tansy problems — FAQ
Why is my tansy invasive spreading?
Vigorous rhizomes form dense colonies and it self-seeds freely; it is a listed noxious weed in some US states. Plant with a root barrier or in a contained bed and deadhead before seed set.
Why is my tansy flopping in rich soil?
Tall stems sprawl in fertile ground or shade; grow hard in lean soil and full sun, or cut back by half in early summer for sturdier regrowth.
Why is my tansy aphid infestation?
Aphids cluster on soft new shoots and flower stems; tolerate minor numbers (tansy attracts beneficials) or dislodge with a water jet.
Why is my tansy powdery mildew?
White coating develops on foliage in crowded, humid conditions; thin clumps and improve airflow to prevent it.