Cold hardiness & minimum temperature

Is Crow Garlic (Allium vineale)cold hardy? Hardiness zone & min temp

Also called Crow Garlic, Field Garlic, Wild Onion, Onion Grass.

More about crow garlic

About Crow Garlic

Allium vineale · also called Crow Garlic, Field Garlic · herb

Allium vineale is a bulbous perennial native to Europe, western Asia, and North Africa, naturalised widely across North America and Australasia where it is often considered a noxious weed. It grows in grassy places, roadsides, and disturbed ground, spreading aggressively via underground bulb offsets, aerial bulbils, and seeds. The most important care fact is containment: in garden settings it will self-propagate vigorously and is very difficult to eradicate once established. All Allium species are toxic to cats and dogs.

Cold limit: USDA 4-8 · RHS H6 (-20 to 30°C)

What crow garlic's hardiness rating actually means

Yes — crow garlic is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 4-8 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −20 to −15 °C. Crow Garlic is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for crow garlic as it gets too cold:

It tolerates winter lows to about −20 to −15 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can crow garlic go outside or overwinter — and where?

Plant it out within USDA 4-8 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when crow garlic can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Crow Garlic hardiness — frequently asked questions

Is crow garlic cold hardy?

Yes — crow garlic is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Crow Garlic is hardy across USDA 4-8; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature crow garlic can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Crow Garlic is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is crow garlic?

Crow Garlic is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can crow garlic survive winter outside?

Plant it out within USDA 4-8 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to crow garlic below its minimum temperature?

It tolerates winter lows to about −20 to −15 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.