Repotting guide

When & how to repot Wart Fern (Microsorum scolopendria)

Also called Wart Fern, Oak Leaf Fern, Climbing Bird's Nest Fern.

More about wart fern

About Wart Fern

Microsorum scolopendria · also called Wart Fern, Oak Leaf Fern · houseplant

The wart fern is a creeping epiphytic fern from Pacific and tropical-Asian forests, named for the wart-like sori dotting the undersides of its glossy, deeply lobed fronds. It spreads by a long-running surface rhizome rather than a crown, climbing logs and walls. Grown indoors it rewards bright-indirect light, steady warmth, high humidity, and an open, bark-rich mix.

Mature size: Fronds typically 30-75 cm long indoors; the rhizome can spread well over a metre across a mount or wide pan over time.

How to tell wart fern needs repotting

Repotting on a calendar is less reliable than reading the plant. For wart 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 wart 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 wart fern

Every 1–2 years, disturbing the roots as little as possible. Wart Fern's growth habit — vigorous creeping epiphyte that advances on a thick, scaly surface rhizome, throwing up individual leathery, pinnately lobed fronds along its length; happily climbs bark, mounts or a moss pole. — sets the pace. The wart fern is a creeping epiphytic fern from Pacific and tropical-Asian forests, named for the wart-like sori dotting the undersides of its glossy, deeply lobed fronds. It spreads by a long-running surface rhizome rather than a crown, climbing logs and walls. Grown indoors it rewards bright-indirect light, steady warmth, high humidity, and an open, bark-rich mix.

What size pot to step wart fern up to

Go up only one size and handle the rootball as little as possible. Wart 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 wart fern

Early spring, just as new growth restarts, is the ideal window for wart 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 wart fern

Keep disturbance to a minimum. Wart 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 loose, fast-draining epiphytic mix ready.
Slide the rootball out whole. Water the day before, then ease wart 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 wart 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 wart fern

Wart Fern wants loose, fast-draining epiphytic mix. Use an airy blend of orchid bark, coco coir or peat-free compost, perlite and a little sphagnum. The running rhizome should sit on or just at the surface, not be buried, so it stays aerated and free-draining. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting wart fern — frequently asked questions

How often should you repot wart fern?

Every 1–2 years, disturbing the roots as little as possible for wart fern. Repot wart 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 loose, fast-draining epiphytic mix, keep it warm and humid afterwards, and never bare-root or hard-prune the roots.

What size pot does wart fern need?

When is the best time of year to repot wart fern?

Why does wart fern sulk after repotting?

Wart 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 wart fern after repotting?

Not immediately. Wait about 4 weeks after repotting wart 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.