Cold hardiness & minimum temperature

Is Corn Salad (Valerianella locusta)cold hardy? Hardiness zone & min temp

Also called Corn Salad, Lamb's Lettuce, Mâche, Field Salad.

More about corn salad

About Corn Salad

Valerianella locusta · also called Corn Salad, Lamb's Lettuce · edible

Corn salad (mâche) is a cool-season salad green with mild, nutty-flavoured rosette leaves harvested baby or mature. Extremely cold-hardy, it thrives in autumn, winter, and early spring when most salad crops fail. Quick to mature at 45–60 days, it self-seeds freely and is a staple of year-round salad growing in temperate UK and US climates.

Cold limit: USDA 3-9 (hardy cool-season annual/biennial; survives frost to -10°C with protection) · RHS H5 (4–18°C)

Watch for — Damping off (Pythium, Rhizoctonia spp.): Seedlings collapse at soil level in cold, wet, poorly ventilated conditions — most common under glass in autumn. Use fresh, sterile compost, sow thinly, and ventilate cloches and cold frames on mild days to reduce excess humidity.

What corn salad's hardiness rating actually means

Hardiness works differently for corn salad: 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 H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 3-9 (hardy cool-season annual/biennial; survives frost to -10°C with protection) — 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 corn salad 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 corn salad 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 corn salad can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Frost protection for borderline corn salad

Corn Salad 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.

Corn Salad hardiness — frequently asked questions

Is corn salad cold hardy?

Hardiness works differently for corn salad: 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. Corn Salad is grown 3-9 (hardy cool-season annual/biennial; survives frost to -10°C with protection); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature corn salad 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 corn salad?

Corn Salad is rated USDA 3-9 (hardy cool-season annual/biennial; survives frost to -10°C with protection) and RHS H5 — Hardy in most of the UK and in cold winters.

Can corn salad 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 corn salad 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.