Cold hardiness & minimum temperature

Is Green Cabomba (Cabomba caroliniana)cold hardy? Hardiness zone & min temp

Also called Green Cabomba, Carolina Fanwort, Green Fanwort, Fish Grass.

More about green cabomba

About Green Cabomba

Cabomba caroliniana · also called Green Cabomba, Carolina Fanwort · tropical

Green Cabomba is a widely cultivated aquarium stem plant from the Americas, forming feathery, bright-green fan-shaped whorls of finely divided leaves. A fast grower in good conditions, it provides excellent oxygenation and spawning cover for fish. It is considered an invasive species in several countries and must never be released into waterways. Not listed as toxic by the ASPCA.

Cold limit: USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways) · RHS H4 (18-26°C)

Watch for — Falling apart or shedding leaves: Usually caused by water that is too warm, too hard, or low in nutrients; check temperature and water chemistry and supplement micronutrients.

What green cabomba's hardiness rating actually means

Yes — green cabomba is genuinely cold hardy. Rated RHS H4 and USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways) — 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 to −5 °C. Green Cabomba is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for green cabomba as it gets too cold:

It tolerates winter lows to about −10 to −5 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can green cabomba go outside or overwinter — and where?

Plant it out within USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways) and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

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 green cabomba can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Green Cabomba hardiness — frequently asked questions

Is green cabomba cold hardy?

Yes — green cabomba is genuinely cold hardy. Rated RHS H4 and USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Green Cabomba is hardy across USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways); it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature green cabomba can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Green Cabomba is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is green cabomba?

Green Cabomba is rated USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can green cabomba survive winter outside?

Plant it out within USDA 6-11 (in the wild; keep controlled in aquariums — DO NOT release into natural waterways) and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to green cabomba below its minimum temperature?

It tolerates winter lows to about −10 to −5 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.