Cold hardiness & minimum temperature

Is Medusa's Cirrhopetalum (Cirrhopetalum medusae)cold hardy? Hardiness zone & min temp

Also called Medusa Orchid, Bulbophyllum medusae, Threadlike Cirrhopetalum.

More about medusa's cirrhopetalum

About Medusa's Cirrhopetalum

Cirrhopetalum medusae · also called Medusa Orchid, Bulbophyllum medusae · tropical

Medusa's Cirrhopetalum (syn. Bulbophyllum medusae) is a striking epiphytic orchid from Southeast Asia, producing extraordinary umbels of creamy-white flowers with extremely long, thread-like, twisted sepals that resemble Medusa's hair. It is widely grown for its bizarre ornamental appeal. ASPCA recognises Bulbophyllum (Cirrhopetalum) as non-toxic to pets.

Cold limit: USDA 11-12 (warm-growing; minimum 15°C required) · RHS H1c (15-30°C)

Watch for — Flower bud blast: Buds drop before opening if the plant is moved or exposed to temperature fluctuations during the bud development stage. Keep conditions stable when buds are forming.

What medusa's cirrhopetalum's hardiness rating actually means

Medusa's Cirrhopetalum 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 11-12 (warm-growing; minimum 15°C required) — 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 5 °C (and never frost). Medusa's Cirrhopetalum has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for medusa's cirrhopetalum as it gets too cold:

Below about about 5 °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 medusa's cirrhopetalum go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 medusa's cirrhopetalum can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Medusa's Cirrhopetalum hardiness — frequently asked questions

Is medusa's cirrhopetalum cold hardy?

Medusa's Cirrhopetalum 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. Medusa's Cirrhopetalum can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (warm-growing; minimum 15°C required)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature medusa's cirrhopetalum can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Medusa's Cirrhopetalum has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is medusa's cirrhopetalum?

Medusa's Cirrhopetalum is rated USDA 11-12 (warm-growing; minimum 15°C required) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can medusa's cirrhopetalum survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 medusa's cirrhopetalum below its minimum temperature?

Below about about 5 °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.