Cold hardiness & minimum temperature

Is Hydrocotyle leucocephala (Hydrocotyle leucocephala)cold hardy? Hardiness zone & min temp

Also called Brazilian pennywort, white-head pennywort.

More about hydrocotyle leucocephala

About Hydrocotyle leucocephala

Hydrocotyle leucocephala · also called Brazilian pennywort, white-head pennywort · tropical

Hydrocotyle leucocephala, Brazilian pennywort, is a fast, easy stem plant with round scalloped leaves on long trailing stems. Hardy and undemanding, it grows submerged, floating or emersed and tolerates low light without CO2. It is excellent for absorbing excess nutrients and offering shade and cover, but needs regular trimming to control its rapid growth.

Cold limit: USDA Tropical aquarium plant; not frost-hardy, kept in heated aquaria (20-28°C)

What hydrocotyle leucocephala's hardiness rating actually means

Hydrocotyle leucocephala 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, kept in heated aquaria — 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). Hydrocotyle leucocephala has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hydrocotyle leucocephala hardiness — frequently asked questions

Is hydrocotyle leucocephala cold hardy?

Hydrocotyle leucocephala 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. Hydrocotyle leucocephala can only live outside year-round in genuinely frost-free climates (roughly USDA Tropical aquarium plant; not frost-hardy, kept in heated aquaria); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature hydrocotyle leucocephala can survive?

What hardiness zone is hydrocotyle leucocephala?

Hydrocotyle leucocephala is rated USDA Tropical aquarium plant; not frost-hardy, kept in heated aquaria and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can hydrocotyle leucocephala 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 hydrocotyle leucocephala 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.