Cold hardiness & minimum temperature

Is Zucchini / courgette (Cucurbita pepo)cold hardy? Hardiness zone & min temp

Also called courgette, summer squash, marrow (mature fruit).

About Zucchini / courgette

Cucurbita pepo · also called courgette, summer squash · edible

Zucchini (US) or courgette (UK) is a fast-growing summer squash that crops heavily through summer. One or two plants feed a household. Needs sun, rich soil, and steady water. Pet-safe; fruit and foliage are non-toxic.

Zucchini is a summer-squash form of Cucurbita pepo, a species domesticated in Mesoamerica thousands of years ago; the modern cylindrical zucchini was selected in 19th-century Milan, Italy.

Bush and vining types exist; direct-seeding is preferred since transplants suffer in cold soil. Harvest fruit frequently while young, before skins harden and seeds enlarge.

Cold limit: USDA Grown as an annual in zones 3-11 · RHS H2 (tender) (18-29°C)

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

What zucchini / courgette's hardiness rating actually means

Hardiness works differently for zucchini / courgette: 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA Grown as an annual in zones 3-11 — 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 zucchini / courgette 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 zucchini / courgette 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 zucchini / courgette can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline zucchini / courgette

Zucchini / courgette 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.

Zucchini / courgette hardiness — frequently asked questions

Is zucchini / courgette cold hardy?

Hardiness works differently for zucchini / courgette: 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. Zucchini / courgette is grown Grown as an annual in zones 3-11; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature zucchini / courgette 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 zucchini / courgette?

Zucchini / courgette is rated USDA Grown as an annual in zones 3-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can zucchini / courgette 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 zucchini / courgette 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.