Cold hardiness & minimum temperature

Is Red Cabbage (Brassica oleracea var. capitata f. rubra 'Red Drumhead')cold hardy? Hardiness zone & min temp

Also called red cabbage, purple cabbage.

More about red cabbage

About Red Cabbage

Brassica oleracea var. capitata f. rubra 'Red Drumhead' · also called red cabbage, purple cabbage · edible

Red cabbage is a firm-headed cabbage with dense, deep-purple, anthocyanin-rich leaves storing well after harvest. It needs a long season in full sun and firm, fertile, alkaline-leaning soil with steady moisture. Net against cabbage pests, feed generously, and harvest the solid heads in autumn; many keep for weeks in cool storage.

Cold limit: USDA 6-9 (autumn/winter harvest); grown as an annual in zones 1-9 · RHS H4 (7-24°C)

What red cabbage's hardiness rating actually means

Hardiness works differently for red cabbage: it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6-9 (autumn/winter harvest); grown as an annual in zones 1-9 — 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

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

Concretely, for red cabbage as it gets too cold:

Light frost (around 0 to −2 °C) damages or kills tender summer crops outright; cold-hardy types take a few degrees of frost.
The plant does not "survive winter" — its life cycle simply ends, by design, when frost arrives or it finishes cropping.
A surprise late spring frost can also kill young transplants set out too early, before the season even starts.

Can red cabbage go outside or overwinter — and where?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost.
In short-season zones, start it indoors or under cover to stretch the effective growing window.
Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

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 red cabbage can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline red cabbage

Red Cabbage is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks.
Have row cover ready for an unexpected late spring or early autumn frost.
Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.

Red Cabbage hardiness — frequently asked questions

Is red cabbage cold hardy?

Hardiness works differently for red cabbage: it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". A seasonal crop, not a perennial. Red Cabbage is grown 6-9 (autumn/winter harvest); grown as an annual in zones 1-9; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature red cabbage can survive?

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

What hardiness zone is red cabbage?

Red Cabbage is rated USDA 6-9 (autumn/winter harvest); grown as an annual in zones 1-9 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can red cabbage survive winter outside?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost. In short-season zones, start it indoors or under cover to stretch the effective growing window. Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

How do I protect red cabbage from frost?

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks. Have row cover ready for an unexpected late spring or early autumn frost. Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.