Cold hardiness & minimum temperature

Is Ruby Necklace (Othonna capensis)cold hardy? Hardiness zone & min temp

Also called Ruby Necklace, String of Rubies, Little Pickles, Trailing Othonna, Cape Aster.

More about ruby necklace

About Ruby Necklace

Othonna capensis · also called Ruby Necklace, String of Rubies · houseplant

Ruby Necklace (Othonna capensis, syn. Crassothonna capensis) is a trailing South African succulent with bean-shaped leaves on purple stems that flush ruby-red in bright light, plus tiny yellow daisy flowers. Give it bright light, gritty fast-draining soil and sparing water. It is not ASPCA-listed; treat as mildly toxic and verify with a vet.

Cold limit: USDA USDA 9b-11 (frost-tender; grow as a houseplant or move indoors below ~50 F / 10 C) (18-27 C (keep above ~10 C; hardy to about -1 C))

Watch for — Mushy, translucent stems / root rot: The most common problem, caused by overwatering or soil that holds moisture. Let the mix dry out fully between waterings, use a gritty fast-draining medium and a pot with drainage holes, and cut back hard on water in winter.

What ruby necklace's hardiness rating actually means

Ruby Necklace 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 USDA 9b-11 (frost-tender; grow as a houseplant or move indoors below ~50 F / 10 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). Ruby Necklace has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Ruby Necklace hardiness — frequently asked questions

Is ruby necklace cold hardy?

Ruby Necklace 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. Ruby Necklace can only live outside year-round in genuinely frost-free climates (roughly USDA USDA 9b-11 (frost-tender; grow as a houseplant or move indoors below ~50 F / 10 C)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature ruby necklace can survive?

What hardiness zone is ruby necklace?

Ruby Necklace is rated USDA USDA 9b-11 (frost-tender; grow as a houseplant or move indoors below ~50 F / 10 C) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can ruby necklace 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 ruby necklace 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.