Troubleshooting
Tall Coreopsis problems — and how to fix them
Tall Coreopsis (Coreopsis tripteris) 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.
Lodging (flopping over)
Very tall stems may topple in windy sites or rich soils. Stake plants in exposed locations, cut back stems by one-quarter in late spring (Chelsea chop), or site in slightly lean soil to limit height.
Crown rot in wet soils
Poorly drained or waterlogged soil causes crown and root rot, especially over winter. Plant on a slope or raised bed, or amend clay with grit to improve drainage.
Leaf spot (Septoria/Cercospora)
Brown spots with yellow halos appear on leaves in warm, wet summers. Remove affected leaves, avoid wetting foliage, and space plants adequately for airflow. Rarely fatal.
Prevent tall coreopsis problems before they start
Most tall coreopsis issues are care-mismatch, not bad luck. Dial in the basics:
Looking for tall coreopsis in general rather than its problems? Read the full tall coreopsis care guide — light, water, soil and feeding.
Tall Coreopsis problems — FAQ
Why is my tall coreopsis lodging (flopping over)?
Very tall stems may topple in windy sites or rich soils. Stake plants in exposed locations, cut back stems by one-quarter in late spring (Chelsea chop), or site in slightly lean soil to limit height.
Why is my tall coreopsis crown rot in wet soils?
Poorly drained or waterlogged soil causes crown and root rot, especially over winter. Plant on a slope or raised bed, or amend clay with grit to improve drainage.
Why is my tall coreopsis leaf spot (septoria/cercospora)?
Brown spots with yellow halos appear on leaves in warm, wet summers. Remove affected leaves, avoid wetting foliage, and space plants adequately for airflow. Rarely fatal.