Cold hardiness & minimum temperature

Is Turnip 'Hakurei' (Brassica rapa var. rapa 'Hakurei')cold hardy? Hardiness zone & min temp

Also called Hakurei turnip, Japanese salad turnip, white salad turnip.

More about turnip 'hakurei'

About Turnip 'Hakurei'

Brassica rapa var. rapa 'Hakurei' · also called Hakurei turnip, Japanese salad turnip · edible

'Hakurei' is a premium F1 Japanese salad turnip with smooth, pure-white roots that are sweet, crisp and mild enough to eat raw like fruit. Fast to mature in about 38-50 days, both roots and tender greens are prized. Bolt-tolerant and refined in flavour, it is sown direct in full sun in cool spring or autumn weather.

Cold limit: USDA 2-9 (grown as a cool-season crop) · RHS H4 (10-20°C)

What turnip 'hakurei''s hardiness rating actually means

Hardiness works differently for turnip 'hakurei': 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 2-9 (grown as a cool-season crop) — 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 turnip 'hakurei' 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 turnip 'hakurei' 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 turnip 'hakurei' 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 turnip 'hakurei'

Turnip 'Hakurei' 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.

Turnip 'Hakurei' hardiness — frequently asked questions

Is turnip 'hakurei' cold hardy?

Hardiness works differently for turnip 'hakurei': 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. Turnip 'Hakurei' is grown as an annual in USDA 2-9 (grown as a cool-season crop); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature turnip 'hakurei' 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 turnip 'hakurei'?

Turnip 'Hakurei' is rated USDA 2-9 (grown as a cool-season crop) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can turnip 'hakurei' 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 turnip 'hakurei' 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.