Overwintering guide
How to overwinter slender waterweed
Winter watering
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
The mistake that kills slender waterweed in winter
Cutting slender waterweed 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 slender waterweed care
Overwintering slender waterweed — FAQ
Does slender waterweed need to come indoors for winter?
Slender Waterweed is hardy to roughly USDA zone 5 — winter lows around -29°C. That means it can stay outside all winter in most temperate gardens. Slender Waterweed 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 slender waterweed for winter?
Tidy and mulch in late autumn; leave the plant undisturbed until spring.
How often should I water slender waterweed in winter?
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
What kills slender waterweed over winter?
Cutting slender waterweed 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.