Cold hardiness & minimum temperature

Is Wild Radish (Raphanus raphanistrum subsp. sativus)cold hardy? Hardiness zone & min temp

Also called Wild Radish, Jointed Charlock, White Charlock, Wild Kale.

More about wild radish

About Wild Radish

Raphanus raphanistrum subsp. sativus · also called Wild Radish, Jointed Charlock · edible

Wild radish is the weedy ancestor of cultivated radishes, widely foraged for its peppery young leaves, seedpods, and flowers. It is a fast-growing cool-season annual or biennial, highly adaptable to disturbed ground. Young foliage and immature green seedpods are edible raw or cooked; mature seeds can be pressed for oil.

Cold limit: USDA 3–11 (cool-season annual/biennial) · RHS H5 (5–22°C)

What wild radish's hardiness rating actually means

Hardiness works differently for wild radish: 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 H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 3–11 (cool-season annual/biennial) — 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 wild radish 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 wild radish 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 wild radish can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Frost protection for borderline wild radish

Wild Radish 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.

Wild Radish hardiness — frequently asked questions

Is wild radish cold hardy?

Hardiness works differently for wild radish: 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. Wild Radish is grown 3–11 (cool-season annual/biennial); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature wild radish 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 wild radish?

Wild Radish is rated USDA 3–11 (cool-season annual/biennial) and RHS H5 — Hardy in most of the UK and in cold winters.

Can wild radish 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 wild radish 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.