Cold hardiness & minimum temperature

Is Buttonwood Bonsai (Conocarpus erectus)cold hardy? Hardiness zone & min temp

Also called buttonwood, buttonwood bonsai, silver buttonwood.

More about buttonwood bonsai

About Buttonwood Bonsai

Conocarpus erectus · also called buttonwood, buttonwood bonsai · houseplant

Buttonwood is a coastal mangrove-associate beloved in bonsai for its dramatic, weathered deadwood and twisting silvery trunks collected from Florida and the Caribbean. The silver form carries soft grey, fuzzy leaves. It is a sun-loving, salt-tolerant tropical that demands warmth and heat, making it a specialist's tree rather than a casual indoor subject.

Cold limit: USDA 10-11 (frost-sensitive; protect below about 10°C) (20-32°C)

Watch for — Cold damage: A frost-tender tropical; temperatures near or below 10°C cause dieback. Bring it into warmth well before any chill and never expose it to frost.

What buttonwood bonsai's hardiness rating actually means

Buttonwood Bonsai 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 10-11 (frost-sensitive; protect below about 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 5 °C (and never frost). Buttonwood Bonsai has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for buttonwood bonsai 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 buttonwood bonsai 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 buttonwood bonsai can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Buttonwood Bonsai hardiness — frequently asked questions

Is buttonwood bonsai cold hardy?

Buttonwood Bonsai 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. Buttonwood Bonsai can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (frost-sensitive; protect below about 10°C)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature buttonwood bonsai can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Buttonwood Bonsai has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is buttonwood bonsai?

Buttonwood Bonsai is rated USDA 10-11 (frost-sensitive; protect below about 10°C) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can buttonwood bonsai 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 buttonwood bonsai 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.