Troubleshooting
Cosmos 'Sensation' problems — and how to fix them
Cosmos 'Sensation' (Cosmos bipinnatus 'Sensation') 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.
Leggy, floppy growth
Too rich a soil, too much water or shade makes stems stretch and collapse. Grow lean and sunny, and stake tall varieties or pinch young plants to bush out.
Few flowers
Excess nitrogen drives leafy growth at the expense of blooms. Withhold fertiliser and deadhead regularly to keep flowers coming.
Aphids
Cluster on soft new tips and buds. Blast off with water or tolerate, as they rarely harm an established plant.
Powdery mildew
Grey coating in humid, crowded conditions. Thin plants for airflow and remove badly affected stems.
Prevent cosmos 'sensation' problems before they start
Most cosmos 'sensation' issues are care-mismatch, not bad luck. Dial in the basics:
- Common cosmos problems — the species this cultivar belongs to
- What's wrong with my plant? — the diagnosis apps compared
- Cosmos 'Sensation' watering schedule
- Cosmos 'Sensation' light requirements
- Best soil mix for cosmos 'sensation'
- Cosmos 'Sensation' temperature & humidity
- Full cosmos 'sensation' care guide
Looking for cosmos 'sensation' in general rather than its problems? Read the full cosmos 'sensation' care guide — light, water, soil and feeding.
Cosmos 'Sensation' problems — FAQ
Why is my cosmos 'sensation' leggy, floppy growth?
Too rich a soil, too much water or shade makes stems stretch and collapse. Grow lean and sunny, and stake tall varieties or pinch young plants to bush out.
Why is my cosmos 'sensation' few flowers?
Excess nitrogen drives leafy growth at the expense of blooms. Withhold fertiliser and deadhead regularly to keep flowers coming.
Why is my cosmos 'sensation' aphids?
Cluster on soft new tips and buds. Blast off with water or tolerate, as they rarely harm an established plant.
Why is my cosmos 'sensation' powdery mildew?
Grey coating in humid, crowded conditions. Thin plants for airflow and remove badly affected stems.