Cold hardiness & minimum temperature

Is Welwitsch's Anchomanes (Anchomanes welwitschii)cold hardy? Hardiness zone & min temp

Also called Welwitsch Anchomanes, African Forest Arum.

More about welwitsch's anchomanes

About Welwitsch's Anchomanes

Anchomanes welwitschii · also called Welwitsch Anchomanes, African Forest Arum · tropical

Anchomanes welwitschii is a large, dramatic tuberous aroid from tropical West and Central African forests, producing a solitary compound leaf of enormous size on a prickly stem that emerges before or with the spathe. Rarely seen outside specialist collections. As an aroid it contains calcium oxalate crystals and is toxic to pets and humans.

Cold limit: USDA 10-12 (indoor-only in most climates) · RHS H1b (18-28°C)

What welwitsch's anchomanes's hardiness rating actually means

Welwitsch's Anchomanes 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 10-12 (indoor-only 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

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

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

Welwitsch's Anchomanes hardiness — frequently asked questions

Is welwitsch's anchomanes cold hardy?

Welwitsch's Anchomanes 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. Welwitsch's Anchomanes can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor-only in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature welwitsch's anchomanes can survive?

What hardiness zone is welwitsch's anchomanes?

Welwitsch's Anchomanes is rated USDA 10-12 (indoor-only in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can welwitsch's anchomanes 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 welwitsch's anchomanes 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.