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