Overwintering guide
How to overwinter purple giant hyssop
Winter watering
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
The mistake that kills purple giant hyssop in winter
Cutting purple giant hyssop 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 purple giant hyssop care
Overwintering purple giant hyssop — FAQ
Does purple giant hyssop need to come indoors for winter?
Purple Giant Hyssop is hardy to roughly USDA zone 4 — winter lows around -34°C. That means it can stay outside all winter in most temperate gardens. Purple Giant Hyssop 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 purple giant hyssop for winter?
Tidy and mulch in late autumn; leave the plant undisturbed until spring.
How often should I water purple giant hyssop in winter?
No winter watering needed in open ground. Containers only need water in long dry, frost-free spells.
What kills purple giant hyssop over winter?
Cutting purple giant hyssop 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.