Cold hardiness & minimum temperature

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

Also called Tokyo Cross turnip, Japanese turnip, hakurei-type turnip.

More about turnip 'tokyo cross'

About Turnip 'Tokyo Cross'

Brassica rapa var. rapa 'Tokyo Cross' · also called Tokyo Cross turnip, Japanese turnip · edible

'Tokyo Cross' is an F1 Japanese turnip producing uniform, smooth white globes very fast, often in just 35-40 days. Mild, sweet and tender, it can be eaten raw and rarely turns woody if harvested young. Bolt-resistant and reliable, it suits successional sowing through the season. Sow direct in full sun in cool conditions.

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

What turnip 'tokyo cross''s hardiness rating actually means

Hardiness works differently for turnip 'tokyo cross': 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 'tokyo cross' 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 'tokyo cross' 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 'tokyo cross' 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 'tokyo cross'

Turnip 'Tokyo Cross' 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 'Tokyo Cross' hardiness — frequently asked questions

Is turnip 'tokyo cross' cold hardy?

Hardiness works differently for turnip 'tokyo cross': 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 'Tokyo Cross' 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 'tokyo cross' 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 'tokyo cross'?

Turnip 'Tokyo Cross' 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 'tokyo cross' 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 'tokyo cross' 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.