Soil & potting mix
Best soil for 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.
Preferred mix: Rich, moisture-retentive terrestrial mix
Why nun's orchid needs this mix
Nun's Orchid is an epiphyte — in the wild its roots grip tree bark in open air, so it must be grown in chunky bark, never in potting soil.
- Nun's Orchid's thick green roots photosynthesise and need air and light — bark holds them loosely while letting them breathe and dry between waterings.
- Bark drains almost instantly, then dries, which is exactly the soak-then-dry cycle an epiphyte root expects on a tree branch.
- The chunky structure stops the roots ever sitting in stagnant water, the single thing they cannot tolerate.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons nun's orchid struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- Potting soil suffocates nun's orchid within months — the roots stay wet, go brown and hollow, and the plant slowly collapses even while the leaves look fine at first.
- Fine, broken-down old bark behaves like soil and is the leading cause of orchid root rot — this is why the medium itself has a shelf life.
- Packing moss tightly around the roots traps water against them and rots them just as fast as soil.
Ever using ordinary compost or "houseplant soil" for nun's orchid, or leaving it in old, decomposed bark for years. Fresh, coarse bark is non-negotiable.
pH — does it matter for nun's orchid?
Orchid bark sits slightly acidic (around pH 5.5-6.5) as it ages, which suits nun's orchid well. Testing pH is unnecessary; replacing spent bark on time matters far more.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
Bagged "orchid bark mix" is genuinely good for nun's orchid and the easiest correct choice — just buy a coarse grade, not fine. Adding a little perlite or charcoal from the ratio above extends its life.
Drainage and the pot
Use a pot with many holes (or a clear orchid pot) so roots get air and light and water never pools. Stand it in a cover pot only briefly while it drains, then tip every drop away.
Bark decomposes — repot nun's orchid into fresh coarse bark every 1-2 years, ideally just after flowering, the moment the mix starts to look broken-down and soggy. When the time comes, our repotting guide for nun's orchid covers the timing and technique step by step.
Nun's Orchid soil — frequently asked questions
What is the best soil mix for nun's orchid?
4 parts coarse fir or pine orchid bark : 1 part perlite or horticultural charcoal : 1 part sphagnum moss (optional, for dry homes). Nun's Orchid's thick green roots photosynthesise and need air and light — bark holds them loosely while letting them breathe and dry between waterings.
Can I use normal potting soil for nun's orchid?
Potting soil suffocates nun's orchid within months — the roots stay wet, go brown and hollow, and the plant slowly collapses even while the leaves look fine at first. Bagged "orchid bark mix" is genuinely good for nun's orchid and the easiest correct choice — just buy a coarse grade, not fine. Adding a little perlite or charcoal from the ratio above extends its life.
Does nun's orchid need a special pH?
Orchid bark sits slightly acidic (around pH 5.5-6.5) as it ages, which suits nun's orchid well. Testing pH is unnecessary; replacing spent bark on time matters far more.
Should I buy a bagged mix or make my own for nun's orchid?
Bagged "orchid bark mix" is genuinely good for nun's orchid and the easiest correct choice — just buy a coarse grade, not fine. Adding a little perlite or charcoal from the ratio above extends its life.
How often should I refresh the soil for nun's orchid?
Bark decomposes — repot nun's orchid into fresh coarse bark every 1-2 years, ideally just after flowering, the moment the mix starts to look broken-down and soggy. Use a pot with many holes (or a clear orchid pot) so roots get air and light and water never pools. Stand it in a cover pot only briefly while it drains, then tip every drop away.
Keep reading
- Nun's Orchid care — the full brief (light, water, humidity, problems, pet safety)
- How often to water nun's orchid — the schedule the mix feeds into
- Repotting nun's orchid — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Root rot — how the wrong soil starts it, and how to save the plant
- Overwatered plant — signs and recovery
- Why is my plant wilting? Wet vs dry diagnosis
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- All 1284 soil and potting-mix guides in the Growli library