Repotting guide

When & how to repot Soft Tree Fern (Dicksonia antarctica)

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.

Mature size: Trunk can eventually reach 3-5 m over decades, with a frond crown spreading 2-4 m wide; much smaller and slower in containers.

How to tell soft tree fern needs repotting

Repotting on a calendar is less reliable than reading the plant. For soft tree fern, watch for these signs:

Roots creeping out of the drainage holes or matting tightly across the soil surface.
The rootball dries out within a day or two no matter how much you water.
Water channels straight down the gap between rootball and pot without wetting the centre.
Steady decline — thin growth, persistent crispy edges — that good humidity and watering have not fixed. Only then is the disturbance of a repot worth the risk for soft tree fern.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot soft tree fern

Every 1–2 years, disturbing the roots as little as possible. Soft Tree Fern's growth habit — slow-growing evergreen tree fern building an upright fibrous trunk (actually a mass of aerial roots and old frond bases) topped by a spreading crown of fronds. growth is famously slow, often only a few centimetres of trunk per year. — sets the pace. 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.

What size pot to step soft tree fern up to

Go up only one size and handle the rootball as little as possible. Soft Tree Fern resents root disturbance, so the goal is to slide the intact rootball into slightly more soil — not to tease, wash or prune the roots. A modest step up means less shock and a faster recovery.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot soft tree fern

Early spring, just as new growth restarts, is the ideal window for soft tree fern. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting soft tree fern

Keep disturbance to a minimum. Soft Tree Fern resents root disturbance, so the plan is to move the intact rootball — not to wash, tease or prune the roots.
Choose just one size up. Pick a pot only one size larger with drainage, and have moisture-retentive rich, moist, free-draining acidic humus ready.
Slide the rootball out whole. Water the day before, then ease soft tree fern out keeping the rootball intact. Gently free only the roots that are circling the very bottom.
Nestle it into fresh soil. Add a base layer of fresh mix, set the rootball in at the same depth, and backfill gently around the sides without packing hard.
Water and protect. Water in, then keep it warm, humid and out of direct sun for a few weeks while it re-roots. Expect a short sulk — that is normal.

Aftercare

Expect soft tree fern to sulk for a couple of weeks — that is normal after any root disturbance for this group. Keep it warm, humid and out of direct sun, water just enough to keep the mix lightly moist, and do not panic and overwater while it re-roots. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for soft tree fern

Soft Tree Fern wants rich, moist, free-draining acidic humus. Wants a fertile, organic, moisture-retentive but well-drained mix high in leaf mould or composted bark. Avoid alkaline or compacted soils. Mulch the base to hold moisture. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting soft tree fern — frequently asked questions

How often should you repot soft tree fern?

Every 1–2 years, disturbing the roots as little as possible for soft tree fern. Repot soft tree fern every 1–2 years, disturbing the roots as little as possible — it sulks for weeks if the rootball is teased apart. Slide it into one size up in spring with fresh rich, moist, free-draining acidic humus, keep it warm and humid afterwards, and never bare-root or hard-prune the roots.

What size pot does soft tree fern need?

When is the best time of year to repot soft tree fern?

Why does soft tree fern sulk after repotting?

Soft Tree Fern resents root disturbance, so a wilt or stall for a week or two after repotting is normal, not a failure. Minimise it by keeping the rootball intact, stepping up just one size, and keeping the plant warm, humid and out of direct sun while it re-roots.

Should you fertilise soft tree fern after repotting?

Not immediately. Wait about 4 weeks after repotting soft tree fern. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.