Cold hardiness & minimum temperature

Is Soft Tree Fern (Dicksonia antarctica)cold hardy? Hardiness zone & min temp

Also called Tasmanian tree fern, Man fern.

More about soft tree fern

About Soft Tree Fern

Dicksonia antarctica · also called Tasmanian tree fern, Man fern · tropical

Soft tree fern is a slow-growing tree fern from the cool, damp forests of Tasmania and south-eastern Australia. It forms a stout fibrous 'trunk' of old leaf bases topped by a crown of huge arching fronds. Surprisingly hardy for a tree fern, it tolerates light frost and is a prized architectural plant in mild gardens.

Cold limit: USDA 9-10 (marginal; needs winter crown protection at the cold end) · RHS H4 (5-24°C)

Watch for — Frost damage to the crown: Hard frost kills the central growing point. In cold areas pack the crown with straw or fleece over winter and protect the trunk top.

What soft tree fern's hardiness rating actually means

Yes — soft tree fern is genuinely cold hardy. Rated RHS H4 and USDA 9-10 (marginal; needs winter crown protection at the cold end), 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 9-10 (marginal; needs winter crown protection at the cold end) — 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. Soft Tree Fern is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for soft tree fern 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 soft tree fern go outside or overwinter — and where?

Plant it out within USDA 9-10 (marginal; needs winter crown protection at the cold end) 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 soft tree fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Soft Tree Fern hardiness — frequently asked questions

Is soft tree fern cold hardy?

Yes — soft tree fern is genuinely cold hardy. Rated RHS H4 and USDA 9-10 (marginal; needs winter crown protection at the cold end), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Soft Tree Fern is hardy across USDA 9-10 (marginal; needs winter crown protection at the cold end); 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 soft tree fern can survive?

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

What hardiness zone is soft tree fern?

Soft Tree Fern is rated USDA 9-10 (marginal; needs winter crown protection at the cold end) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can soft tree fern survive winter outside?

Plant it out within USDA 9-10 (marginal; needs winter crown protection at the cold end) 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 soft tree fern 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.