Cold hardiness & minimum temperature

Is Field Garlic (Allium oleraceum)cold hardy? Hardiness zone & min temp

Also called Field Garlic, Wild Garlic, Crow Garlic.

More about field garlic

About Field Garlic

Allium oleraceum · also called Field Garlic, Wild Garlic · edible

Allium oleraceum is a bulbous perennial native to most of Europe, including the UK, growing in dry grasslands, hedgerows, and arable margins. It produces narrow, hollow leaves and loose umbels of pale-pink to greenish-white flowers in July and August, often mixed with bulbils that aid its spread. The bulb, leaves, and bulbils are all edible and have a mild garlic flavour, useful raw or cooked. Like all members of the Allium genus, it is toxic to cats and dogs due to sulfur-containing organosulfoxide compounds.

Cold limit: USDA 5-9 · RHS H6 (-25 to 28°C)

What field garlic's hardiness rating actually means

Yes — field garlic is genuinely cold hardy. Rated RHS H6 and USDA 5-9, 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 5-9 — 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. Field Garlic is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for field 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 field garlic go outside or overwinter — and where?

Plant it out within USDA 5-9 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 field garlic can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Field Garlic hardiness — frequently asked questions

Is field garlic cold hardy?

Yes — field garlic is genuinely cold hardy. Rated RHS H6 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Field Garlic is hardy across USDA 5-9; 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 field garlic can survive?

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

What hardiness zone is field garlic?

Field Garlic is rated USDA 5-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can field garlic survive winter outside?

Plant it out within USDA 5-9 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 field 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.