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