Cold hardiness & minimum temperature

Is Curly Endive 'Frisee' (Cichorium endivia var. crispum 'Frisee')cold hardy? Hardiness zone & min temp

Also called frisee, curly endive, frizzy endive.

More about curly endive 'frisee'

About Curly Endive 'Frisee'

Cichorium endivia var. crispum 'Frisee' · also called frisee, curly endive · edible

Curly endive, or frisee, forms a low rosette of finely cut, frizzy green leaves with a crisp, pleasantly bitter bite. Blanching the centre by covering the heart for a week or two turns the inner leaves pale yellow, crisp and milder. A fast cool-season salad crop best grown for late summer and autumn cutting.

Cold limit: USDA Cool-season annual; tolerates light frost · RHS H3 (10 to 22°C)

What curly endive 'frisee''s hardiness rating actually means

Hardiness works differently for curly endive 'frisee': 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 Cool-season annual; tolerates light frost — 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 curly endive 'frisee' 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 curly endive 'frisee' 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 curly endive 'frisee' 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 curly endive 'frisee'

Curly Endive 'Frisee' 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.

Curly Endive 'Frisee' hardiness — frequently asked questions

Is curly endive 'frisee' cold hardy?

Hardiness works differently for curly endive 'frisee': 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. Curly Endive 'Frisee' is grown Cool-season annual; tolerates light frost; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature curly endive 'frisee' 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 curly endive 'frisee'?

Curly Endive 'Frisee' is rated USDA Cool-season annual; tolerates light frost and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can curly endive 'frisee' 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 curly endive 'frisee' 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.