Cold hardiness & minimum temperature

Is Echinodorus 'Red Flame' (Echinodorus 'Red Flame')cold hardy? Hardiness zone & min temp

Also called Red Flame sword, red Amazon sword.

More about echinodorus 'red flame'

About Echinodorus 'Red Flame'

Echinodorus 'Red Flame' · also called Red Flame sword, red Amazon sword · tropical

A colourful sword hybrid whose broad leaves emerge green flecked with crimson and mature to deep red-spotted, fiery tones under good light. As hardy as the rest of the genus, it forms a bold rosette centrepiece, feeds heavily through its roots, and rewards bright light and iron dosing with its most intense colouration.

Cold limit: USDA Tropical aquarium plant — not frost hardy; keep indoors above 18°C (22-28°C)

What echinodorus 'red flame''s hardiness rating actually means

Echinodorus 'Red Flame' 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 Tropical aquarium plant — not frost hardy; keep indoors above 18°C — 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). Echinodorus 'Red Flame' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Echinodorus 'Red Flame' hardiness — frequently asked questions

Is echinodorus 'red flame' cold hardy?

Echinodorus 'Red Flame' 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. Echinodorus 'Red Flame' can only live outside year-round in genuinely frost-free climates (roughly USDA Tropical aquarium plant — not frost hardy; keep indoors above 18°C); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature echinodorus 'red flame' can survive?

What hardiness zone is echinodorus 'red flame'?

Echinodorus 'Red Flame' is rated USDA Tropical aquarium plant — not frost hardy; keep indoors above 18°C and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can echinodorus 'red flame' 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 echinodorus 'red flame' 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.