Overwintering guide
How to overwinter rubenza cosmos
Winter watering
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
The mistake that kills rubenza cosmos in winter
Cutting rubenza cosmos hard back in autumn "to tidy up". That removes the growth that shelters the crown, and on some plants removes next season's flower buds entirely.
More rubenza cosmos care
Overwintering rubenza cosmos — FAQ
Does rubenza cosmos need to come indoors for winter?
Rubenza cosmos is hardy to roughly USDA zone 2 — winter lows around -46°C. That means it can stay outside all winter in most temperate gardens. Rubenza cosmos is properly hardy and overwinters outside without fuss. Tidy away anything dead or diseased, apply a mulch over the crown to steady soil temperatures, and otherwise leave it alone — many hardy plants actually need a cold period to flower and grow well the following year. Save hard pruning for the right season rather than doing it in autumn.
When should I move rubenza cosmos for winter?
Tidy and mulch in late autumn; leave the plant undisturbed until spring.
How often should I water rubenza cosmos in winter?
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
What kills rubenza cosmos over winter?
Cutting rubenza cosmos hard back in autumn "to tidy up". That removes the growth that shelters the crown, and on some plants removes next season's flower buds entirely.