Cold hardiness & minimum temperature

Is American Sea Rocket (Cakile edentula)cold hardy? Hardiness zone & min temp

Also called American sea rocket, American searocket, Toothed sea rocket.

More about american sea rocket

About American Sea Rocket

Cakile edentula · also called American sea rocket, American searocket · edible

Cakile edentula is a succulent-leaved annual native to sandy beaches and coastal dunes along the Atlantic and Pacific coasts of North America. Like its European relative, it is a classic beach coloniser adapted to nutrient-poor sand, full sun, salt spray, and shifting substrates. Its leaves, stems, and seed pods are edible with a sharp, radish-like pungency and have long been used by indigenous peoples. It is not known to be toxic to cats or dogs.

Cold limit: USDA 3-10 · RHS H6 (-10 to 30°C)

What american sea rocket's hardiness rating actually means

Hardiness works differently for american sea rocket: 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 H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 3-10 — 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 american sea rocket 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 american sea rocket 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 american sea rocket can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Frost protection for borderline american sea rocket

American Sea Rocket 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.

American Sea Rocket hardiness — frequently asked questions

Is american sea rocket cold hardy?

Hardiness works differently for american sea rocket: 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. American Sea Rocket is grown as an annual in USDA 3-10; you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature american sea rocket 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 american sea rocket?

American Sea Rocket is rated USDA 3-10 and RHS H6 — Hardy throughout the UK and northern Europe.

Can american sea rocket 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 american sea rocket 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.