Troubleshooting
Aster 'October Skies' problems — and how to fix them
Aster 'October Skies' (Symphyotrichum oblongifolium 'October Skies') 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
Rare on 'October Skies' compared to other asters, but possible in humid, stagnant-air conditions. Improve air circulation.
Floppy stems
Caused by excess shade or nitrogen. Grow in full sun with lean soil, or cut back by one-third in early summer (Chelsea chop) to promote bushiness.
Aster yellows (phytoplasma)
Causes distorted, yellowing growth. Spread by leafhoppers; remove and destroy affected plants and control leafhoppers.
Aphids
May cluster on new growth in spring. Knock off with a strong water spray or apply insecticidal soap.
Root rot
Occurs in poorly drained or constantly wet soils. Ensure good drainage and avoid overwatering, especially in heavy clay.
Prevent aster 'october skies' problems before they start
Most aster 'october skies' issues are care-mismatch, not bad luck. Dial in the basics:
Aster 'October Skies' problems — FAQ
Why is my aster 'october skies' powdery mildew?
Rare on 'October Skies' compared to other asters, but possible in humid, stagnant-air conditions. Improve air circulation.
Why is my aster 'october skies' floppy stems?
Caused by excess shade or nitrogen. Grow in full sun with lean soil, or cut back by one-third in early summer (Chelsea chop) to promote bushiness.
Why is my aster 'october skies' aster yellows (phytoplasma)?
Causes distorted, yellowing growth. Spread by leafhoppers; remove and destroy affected plants and control leafhoppers.
Why is my aster 'october skies' aphids?
May cluster on new growth in spring. Knock off with a strong water spray or apply insecticidal soap.
Why is my aster 'october skies' root rot?
Occurs in poorly drained or constantly wet soils. Ensure good drainage and avoid overwatering, especially in heavy clay.