Cold hardiness & minimum temperature

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

Also called Rothschild Bulbophyllum.

More about rothschild's bulbophyllum

About Rothschild's Bulbophyllum

Bulbophyllum rothschildianum · also called Rothschild Bulbophyllum · flowering

Bulbophyllum rothschildianum is a spectacular cool-to-intermediate species from the eastern Himalayan foothills, producing umbels of large, maroon-striped flowers with dramatically elongated, twisting sepal tails. It grows as an epiphyte needing bright shade, high humidity, fresh air, and steady moisture in growth, and is prized by collectors for some of the largest, showiest blooms in the genus.

Cold limit: USDA 10-11 (cool-intermediate greenhouse or indoor culture) · RHS H1b (13-26°C)

Watch for — Bud or spike blast: Developing flowers abort in dry air or unstable temperatures. Hold humidity high and conditions steady once spikes appear to carry blooms to opening.

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 10-11 (cool-intermediate greenhouse or indoor culture) — 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 10-11 (cool-intermediate greenhouse or indoor culture)); 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 10-11 (cool-intermediate greenhouse or indoor culture) 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.