Cold hardiness & minimum temperature

Is New Zealand Spinach (Tetragonia tetragonioides)cold hardy? Hardiness zone & min temp

Also called New Zealand spinach, sea spinach, warrigal greens.

More about new zealand spinach

About New Zealand Spinach

Tetragonia tetragonioides · also called New Zealand spinach, sea spinach · edible

New Zealand spinach is a sprawling, heat-loving leafy green from the fig-marigold family, unrelated to true spinach. It thrives through hot summers without bolting, producing a steady flush of thick, triangular, succulent-textured leaves where ordinary spinach fails. Pick the tender shoot tips regularly; always blanch the leaves before eating to drive off the high oxalates.

Cold limit: USDA 9-11 (frost-tender; grown as a warm-season annual elsewhere) · RHS H2 (15-28°C)

Watch for — Frost damage: Completely frost-tender; a single light frost blackens and kills it. Sow or plant out only after all frost risk has passed.

What new zealand spinach's hardiness rating actually means

Hardiness works differently for new zealand spinach: 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 9-11 (frost-tender; grown as a warm-season annual elsewhere) — 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 new zealand spinach 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 new zealand spinach 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 new zealand spinach 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 new zealand spinach

New Zealand Spinach 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.

New Zealand Spinach hardiness — frequently asked questions

Is new zealand spinach cold hardy?

Hardiness works differently for new zealand spinach: 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. New Zealand Spinach is grown 9-11 (frost-tender; grown as a warm-season annual elsewhere); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature new zealand spinach 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 new zealand spinach?

New Zealand Spinach is rated USDA 9-11 (frost-tender; grown as a warm-season annual elsewhere) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can new zealand spinach 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 new zealand spinach 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.