Cold hardiness & minimum temperature

Is Edamame (Glycine max)cold hardy? Hardiness zone & min temp

Also called Soybean, Edamame bean, Vegetable soybean.

More about edamame

About Edamame

Glycine max · also called Soybean, Edamame bean · edible

Edamame (Glycine max) is a vegetable soybean harvested young, when the fuzzy green pods are plump but still tender. A warm-season annual legume, it grows as a bushy, self-supporting plant needing a long, warm summer. Pods are picked at the immature green stage and steamed or boiled in the pod. Reliable warmth and even moisture during pod fill drive the crop.

Cold limit: USDA Grown as a warm-season annual; best in zones 3-9 with a long warm summer (frost-tender) · RHS H2 (20-30°C)

Watch for — Poor germination in cold soil: Seeds rot if sown too early; wait until soil is reliably above 18°C, or start indoors in cooler climates and transplant carefully.

What edamame's hardiness rating actually means

Hardiness works differently for edamame: 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 a warm-season annual; best in zones 3-9 with a long warm summer (frost-tender) — 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 edamame 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 edamame 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 edamame 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 edamame

Edamame 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.

Edamame hardiness — frequently asked questions

Is edamame cold hardy?

Hardiness works differently for edamame: 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. Edamame is grown Grown as a warm-season annual; best in zones 3-9 with a long warm summer (frost-tender); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature edamame 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 edamame?

Edamame is rated USDA Grown as a warm-season annual; best in zones 3-9 with a long warm summer (frost-tender) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can edamame 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 edamame 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.