Cold hardiness & minimum temperature

Is Britton Perilla (Perilla frutescens 'Britton')cold hardy? Hardiness zone & min temp

Also called Britton Perilla, Shiso, Beefsteak Plant.

More about britton perilla

About Britton Perilla

Perilla frutescens 'Britton' · also called Britton Perilla, Shiso · edible

Britton Perilla is a compact, upright cultivar of shiso with deeply ruffled, dark-green to bronze-tinged leaves and a spicy, anise-mint flavor. Ideal for edible gardens and containers, it thrives in full sun to part shade with regular moisture. A fast-growing annual herb used widely in Asian cuisine, it self-seeds readily in warm climates.

Cold limit: USDA 2–11 (annual) · RHS H1c (18–30°C)

What britton perilla's hardiness rating actually means

Hardiness works differently for britton perilla: 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 2–11 (annual) — 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 britton perilla 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 britton perilla 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 britton perilla can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Frost protection for borderline britton perilla

Britton Perilla 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.

Britton Perilla hardiness — frequently asked questions

Is britton perilla cold hardy?

Hardiness works differently for britton perilla: 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. Britton Perilla is grown 2–11 (annual); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature britton perilla 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 britton perilla?

Britton Perilla is rated USDA 2–11 (annual) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can britton perilla 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 britton perilla 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.