Cold hardiness & minimum temperature

Is Pouch Flower (Calceolaria crenatiflora)cold hardy? Hardiness zone & min temp

Also called Pouch Flower, Pocketbook Plant, Slipper Flower, Lady's Purse.

More about pouch flower

About Pouch Flower

Calceolaria crenatiflora · also called Pouch Flower, Pocketbook Plant · flowering

Calceolaria crenatiflora is a cool-season annual or biennial from Chile, widely grown as a short-lived houseplant or conservatory plant for its spectacular pouched flowers in vivid shades of yellow, orange, and red, often heavily spotted with contrasting colours. It demands consistently cool temperatures (13–18 °C / 55–65 °F) and will deteriorate quickly in typical summer warmth, making it best treated as a spring-flowering gift plant to be enjoyed briefly then composted or, for the patient, raised fresh from seed each autumn. Keeping it away from radiators and draughts is the single most important care rule. The Calceolaria genus is not confirmed individually by the ASPCA; classified here as mildly-toxic as a precaution.

Cold limit: USDA 9-11 (grown as a cool-season annual in most climates) · RHS H1c (7–18 °C)

What pouch flower's hardiness rating actually means

Hardiness works differently for pouch flower: 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 9-11 (grown as a cool-season annual in most climates) — 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 pouch flower 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 pouch flower 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 pouch flower 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 pouch flower

Pouch Flower 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.

Pouch Flower hardiness — frequently asked questions

Is pouch flower cold hardy?

Hardiness works differently for pouch flower: 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. Pouch Flower is grown 9-11 (grown as a cool-season annual in most climates); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature pouch flower 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 pouch flower?

Pouch Flower is rated USDA 9-11 (grown as a cool-season annual in most climates) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can pouch flower 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 pouch flower 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.