Cold hardiness & minimum temperature

Is Saintpaulia 'Mac's Black Pearl' (Saintpaulia 'Mac's Black Pearl')cold hardy? Hardiness zone & min temp

Also called Mac's Black Pearl African violet.

More about saintpaulia 'mac's black pearl'

About Saintpaulia 'Mac's Black Pearl'

Saintpaulia 'Mac's Black Pearl' · also called Mac's Black Pearl African violet · flowering

'Mac's Black Pearl' is a hybrid African violet prized for its near-black, glossy, almost violet-black blooms over standard rosette foliage. Grown as a compact windowsill houseplant, it flowers nearly year-round in bright indirect light with steady warmth, even moisture and high humidity. It stays small, making it ideal for collectors of dark-flowered Saintpaulia cultivars.

Cold limit: USDA 11-12 (indoor houseplant in most US and UK homes) · RHS H1b (18-24°C)

Watch for — Leaf spotting and rings: Pale or brown rings appear where cold water touched the fuzzy leaves. Water at the soil level with room-temperature water and avoid splashing the foliage.

What saintpaulia 'mac's black pearl''s hardiness rating actually means

Saintpaulia 'Mac's Black Pearl' 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 11-12 (indoor houseplant in most US and UK homes) — 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). Saintpaulia 'Mac's Black Pearl' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Saintpaulia 'Mac's Black Pearl' hardiness — frequently asked questions

Is saintpaulia 'mac's black pearl' cold hardy?

Saintpaulia 'Mac's Black Pearl' 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. Saintpaulia 'Mac's Black Pearl' can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor houseplant in most US and UK homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature saintpaulia 'mac's black pearl' can survive?

What hardiness zone is saintpaulia 'mac's black pearl'?

Saintpaulia 'Mac's Black Pearl' is rated USDA 11-12 (indoor houseplant in most US and UK homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can saintpaulia 'mac's black pearl' 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 saintpaulia 'mac's black pearl' 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.