Troubleshooting
Coreopsis 'Route 66' problems — and how to fix them
Coreopsis 'Route 66' (Coreopsis 'Route 66') 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.
Fading bicolour pattern
Flower colour contrast diminishes in excessive heat or if plants are underperforming. Deadhead spent blooms promptly to encourage a fresh flush with strong colour.
Crown rot
Most common in heavy, wet soils. Improve drainage and avoid mulching directly over the crown.
Aphids
May colonise shoot tips. Wash off with water or use insecticidal soap spray.
Aster yellows
Phytoplasma spread by leafhoppers causes distorted, yellowed growth. Remove infected plants immediately; no chemical cure exists.
Decline after several years
Divide clumps every 3-4 years in spring, replanting only vigorous outer sections in fresh soil.
Prevent coreopsis 'route 66' problems before they start
Most coreopsis 'route 66' issues are care-mismatch, not bad luck. Dial in the basics:
Coreopsis 'Route 66' problems — FAQ
Why is my coreopsis 'route 66' fading bicolour pattern?
Flower colour contrast diminishes in excessive heat or if plants are underperforming. Deadhead spent blooms promptly to encourage a fresh flush with strong colour.
Why is my coreopsis 'route 66' crown rot?
Most common in heavy, wet soils. Improve drainage and avoid mulching directly over the crown.
Why is my coreopsis 'route 66' aphids?
May colonise shoot tips. Wash off with water or use insecticidal soap spray.
Why is my coreopsis 'route 66' aster yellows?
Phytoplasma spread by leafhoppers causes distorted, yellowed growth. Remove infected plants immediately; no chemical cure exists.
Why is my coreopsis 'route 66' decline after several years?
Divide clumps every 3-4 years in spring, replanting only vigorous outer sections in fresh soil.