Cold hardiness & minimum temperature

Is Rothschild's Bulbophyllum (Bulbophyllum rothschildianum)cold hardy? Hardiness zone & min temp

Also called Red Pinwheel Orchid, Rothschild's Cirrhopetalum.

More about rothschild's bulbophyllum

About Rothschild's Bulbophyllum

Bulbophyllum rothschildianum · also called Red Pinwheel Orchid, Rothschild's Cirrhopetalum · tropical

Bulbophyllum rothschildianum is a spectacular warm-growing epiphytic orchid from Southeast Asia, bearing distinctive umbels of up to seven deep red flowers with elongated lateral sepals arranged in a pinwheel. Individually listed as non-toxic by the ASPCA. An eye-catching show orchid for intermediate to warm growers.

Cold limit: USDA 11-12 (indoor only) · RHS H1A (18-30°C)

Watch for — Failure to flower: Often caused by insufficient light or consistently warm nights. Ensure bright indirect light and allow a slight temperature drop of 3-5°C at night in autumn to trigger flowering.

What rothschild's bulbophyllum's hardiness rating actually means

Rothschild's Bulbophyllum 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 11-12 (indoor only) — 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). Rothschild's Bulbophyllum has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for rothschild's bulbophyllum 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 rothschild's bulbophyllum 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 rothschild's bulbophyllum can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Rothschild's Bulbophyllum hardiness — frequently asked questions

Is rothschild's bulbophyllum cold hardy?

Rothschild's Bulbophyllum 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. Rothschild's Bulbophyllum can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor only)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature rothschild's bulbophyllum can survive?

What hardiness zone is rothschild's bulbophyllum?

Rothschild's Bulbophyllum is rated USDA 11-12 (indoor only) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can rothschild's bulbophyllum 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 rothschild's bulbophyllum 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.