Cold hardiness & minimum temperature

Is Autumn King Carrot (Daucus carota subsp. sativus 'Autumn King')cold hardy? Hardiness zone & min temp

Also called Autumn King carrot, long carrot.

More about autumn king carrot

About Autumn King Carrot

Daucus carota subsp. sativus 'Autumn King' · also called Autumn King carrot, long carrot · edible

'Autumn King' is a large, vigorous maincrop carrot producing long, broad, deep-orange roots that hold their quality late into the season and stand well in the ground for winter lifting. It needs deep, light soil to reach full length. A cool-season biennial grown as an annual, it matures in roughly 110-120 days — slower but heavy-yielding and good for storage.

Cold limit: USDA 3-10 (cool-season annual; roots tolerate light frost and store well) · RHS H3 (7-24°C)

What autumn king carrot's hardiness rating actually means

Hardiness works differently for autumn king carrot: 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 H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 3-10 (cool-season annual; roots tolerate light frost and store well) — 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 autumn king carrot 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 autumn king carrot 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 autumn king carrot can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline autumn king carrot

Autumn King Carrot 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.

Autumn King Carrot hardiness — frequently asked questions

Is autumn king carrot cold hardy?

Hardiness works differently for autumn king carrot: 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. Autumn King Carrot is grown 3-10 (cool-season annual; roots tolerate light frost and store well); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature autumn king carrot 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 autumn king carrot?

Autumn King Carrot is rated USDA 3-10 (cool-season annual; roots tolerate light frost and store well) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can autumn king carrot 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 autumn king carrot 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.