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