Cold hardiness & minimum temperature

Is Radish (Raphanus sativus)cold hardy? Hardiness zone & min temp

Also called salad radish, French breakfast, daikon (winter type).

About Radish

Raphanus sativus · also called salad radish, French breakfast · edible

Radishes are the quickest crop in the vegetable garden — many salad varieties mature in 25-30 days. Sow successionally for a continuous supply. Winter radishes and daikons take longer but store well. Pet-safe.

The garden radish, Raphanus raphanistrum subsp. sativus, is a fast-maturing root crop in the Brassicaceae, long domesticated across Eurasia and grown for its swollen, peppery hypocotyl-root.

One of the quickest garden crops, with small spring types ready roughly 3-5 weeks after sowing; succession sowing every 2 weeks extends the harvest.

Cold limit: USDA 2-11 · RHS H4 (10-21°C)

Sources: extension.umn.edu, plants.ces.ncsu.edu, almanac.com

What radish's hardiness rating actually means

Hardiness works differently for 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 H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 2-11 — 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 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 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 radish 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 radish

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.

Radish hardiness — frequently asked questions

Is radish cold hardy?

Hardiness works differently for 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. Radish is grown as an annual in USDA 2-11; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature 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 radish?

Radish is rated USDA 2-11 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can 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 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.