Cold hardiness & minimum temperature
Is Pygmy Torch Amaranth (Amaranthus hypochondriacus)cold hardy? Hardiness zone & min temp
Also called Prince's Feather, Grain Amaranth, Red Amaranth.
More about pygmy torch amaranth
About Pygmy Torch Amaranth
Amaranthus hypochondriacus · also called Prince's Feather, Grain Amaranth · flowering
Pygmy Torch Amaranth is a compact selection of grain amaranth with dense, upright, deep crimson flower plumes above dark bronzy-purple foliage. Excellent for contemporary borders, cutting gardens, and dried flower arrangements. The ASPCA lists Amaranthus as toxic to pets; the plants also accumulate nitrates and oxalates which are harmful if consumed.
Cold limit: USDA 2-11 (grown as warm-season annual) · RHS H1c (20-38°C)
What pygmy torch amaranth's hardiness rating actually means
Pygmy Torch Amaranth 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 2-11 (grown as warm-season annual) — 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). Pygmy Torch Amaranth has no frost tolerance at all — it is an indoor plant in any climate with a real winter.
Concretely, for pygmy torch amaranth 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 pygmy torch amaranth 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 pygmy torch amaranth can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.
Pygmy Torch Amaranth hardiness — frequently asked questions
Is pygmy torch amaranth cold hardy?
Pygmy Torch Amaranth 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. Pygmy Torch Amaranth can only live outside year-round in genuinely frost-free climates (roughly USDA 2-11 (grown as warm-season annual)); everywhere else it is a houseplant that summers out at most.
What is the minimum temperature pygmy torch amaranth can survive?
Minimum survivable temperature is roughly about 5 °C (and never frost). Pygmy Torch Amaranth has no frost tolerance at all — it is an indoor plant in any climate with a real winter.
What hardiness zone is pygmy torch amaranth?
Pygmy Torch Amaranth is rated USDA 2-11 (grown as warm-season annual) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.
Can pygmy torch amaranth 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 pygmy torch amaranth 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.
Keep reading
- Pygmy Torch Amaranth care — the full brief (light, water, soil, problems, pet safety)
- USDA hardiness zones — find yours and what grows there
- Is pygmy torch amaranth hardy in the UK? — the RHS-rating version
- RHS hardiness ratings — the UK system explained
- Frost-date calculator — your real outdoor window
- The USDA hardiness zone map, explained
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