Cold hardiness & minimum temperature

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

Also called Shiso, Perilla, Beefsteak plant, Perilla mint, Japanese basil, Purple mint.

More about shiso (perilla)

About Shiso (Perilla)

Perilla frutescens · also called Shiso, Perilla · herb

Shiso (Perilla frutescens) is a fast-growing, mint-family culinary annual prized in Japanese, Korean and Vietnamese cooking for its fragrant green or purple leaves. Give it warm weather, full sun to light shade and steady moisture. It is not ASPCA-listed but contains perilla ketone, so treat it as mildly toxic and keep curious pets away.

Cold limit: USDA Perennial only in USDA zones 10a-11b; grown as a frost-tender warm-season annual in all cooler zones (18-30 C)

Watch for — Frost and cold damage: It is not frost-hardy and collapses at the first frost. Do not plant out until after the last frost and night temperatures stay above about 10 C (50 F); bring containers indoors before cold snaps.

What shiso (perilla)'s hardiness rating actually means

Shiso (Perilla) is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA Perennial only in USDA zones 10a-11b; grown as a frost-tender warm-season annual in all cooler zones — 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

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Shiso (Perilla) has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for shiso (perilla) as it gets too cold:

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can shiso (perilla) go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 shiso (perilla) can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Shiso (Perilla) hardiness — frequently asked questions

Is shiso (perilla) cold hardy?

Shiso (Perilla) is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Shiso (Perilla) can only live outside year-round in genuinely frost-free climates (roughly USDA Perennial only in USDA zones 10a-11b; grown as a frost-tender warm-season annual in all cooler zones); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature shiso (perilla) can survive?

What hardiness zone is shiso (perilla)?

Shiso (Perilla) is rated USDA Perennial only in USDA zones 10a-11b; grown as a frost-tender warm-season annual in all cooler zones and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can shiso (perilla) survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to shiso (perilla) below its minimum temperature?

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.