Repotting guide

When & how to repot Nun's Orchid (Phaius tankervilleae)

Also called Swamp Orchid, Veiled Nun Orchid.

More about nun's orchid

About Nun's Orchid

Phaius tankervilleae · also called Swamp Orchid, Veiled Nun Orchid · flowering

Phaius tankervilleae is a robust terrestrial orchid from Asia and the Pacific, sending up tall spikes of large, reddish-brown flowers backed with white and a rosy, trumpet-shaped lip. Unlike epiphytic orchids it grows in rich, moisture-retentive soil, wanting bright shade, warmth, steady water and feeding in growth, and is among the easiest orchids to grow as a houseplant or shaded garden plant.

Mature size: Foliage 60-90 cm tall and arching; flower spikes can reach 0.9-1.2 m, each carrying numerous flowers up to about 10-12 cm across. Forms a substantial clump over time.

How to tell nun's orchid needs repotting

Repotting on a calendar is less reliable than reading the plant. For nun's orchid, watch for these signs:

The bark medium has broken down into a dark, soggy, soil-like mush that no longer drains.
Roots are climbing out of the pot in all directions (this is normal for nun's orchid and not on its own a reason to repot).
Roots inside the pot are brown, soft and rotting rather than firm and green/silver.
It is about two years since the last repot, or you can smell sour, decomposing bark — repot just after flowering finishes.

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 nun's orchid

Every 1–2 years, when the bark breaks down. Nun's Orchid's growth habit — terrestrial sympodial orchid forming clumps of short, fleshy pseudobulbs at soil level, each bearing several large, broad, pleated leaves. tall, erect flower spikes rise from the base in spring carrying many showy, fragrant trumpet-shaped blooms. — sets the pace. Phaius tankervilleae is a robust terrestrial orchid from Asia and the Pacific, sending up tall spikes of large, reddish-brown flowers backed with white and a rosy, trumpet-shaped lip. Unlike epiphytic orchids it grows in rich, moisture-retentive soil, wanting bright shade, warmth, steady water and feeding in growth, and is among the easiest orchids to grow as a houseplant or shaded garden plant.

What size pot to step nun's orchid up to

Keep nun's orchid in the same size pot, or go up just one, only if the roots have genuinely outgrown it. Orchids flower better slightly snug, and a big pot of bark stays wet and rots the roots. The reason you are repotting is the broken-down bark, not a need for more space — a clear pot lets you watch the roots.

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 nun's orchid

Repot nun's orchid immediately after the flowers have finished, just as new roots or a new growth start to emerge — those fresh roots establish quickly in new bark. Never repot an orchid in full bloom; you will drop the flowers and shock the plant.

Step-by-step: repotting nun's orchid

Repot after flowering. Wait until nun's orchid has finished blooming and is pushing new roots. Soak the pot first so the roots are pliable and less likely to snap.
Remove all the old bark. Slide the plant out and crumble away every scrap of broken-down bark — that soggy mush is the actual problem you are fixing.
Trim dead roots. Cut off any brown, hollow or mushy roots with sterilised snips. Keep all the firm green/silver ones.
Repot into fresh bark. Settle nun's orchid into the same or one-size-up pot of fresh coarse rich, moisture-retentive terrestrial mix, working bark between the roots so there are no big air gaps.
Hold off watering briefly. Mist or wait a few days before the first proper water so any cut roots seal. Then resume the normal soak-and-drain rhythm.

Aftercare

Give nun's orchid a few days before its first proper watering so cut roots seal, then return to the weekly soak-and-drain. Keep it bright, humid and out of direct sun while new roots grip the fresh bark. It may pause growth briefly; that is expected. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for nun's orchid

Nun's Orchid wants rich, moisture-retentive terrestrial mix. Unlike bark-grown orchids, it wants a humus-rich, free-draining potting mix, such as a terrestrial orchid blend or quality potting compost with added bark and perlite. The mix should hold moisture yet drain, supporting its fleshy underground pseudobulbs. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting nun's orchid — frequently asked questions

How often should you repot nun's orchid?

Every 1–2 years, when the bark breaks down for nun's orchid. Repot nun's orchid every 1–2 years — but because the bark medium has broken down and gone soggy, not because it has outgrown the pot. Do it just after flowering, into the same size or one up, using fresh rich, moisture-retentive terrestrial mix. Old, decomposed bark suffocating the roots is the real problem.

What size pot does nun's orchid need?

When is the best time of year to repot nun's orchid?

Why does nun's orchid get repotted if it isn't outgrowing the pot?

Because the bark medium breaks down. Over 1–2 years the chunky bark rots into a dense, soggy, soil-like mush that suffocates the roots — that, not size, is why you repot nun's orchid. Refresh it into fresh coarse bark just after flowering.

Should you fertilise nun's orchid after repotting?

Not immediately. Wait about 3 weeks after repotting nun's orchid. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.