Moth orchid (Phalaenopsis amabilis) care

Flowering · easy to keep

Moth orchid (Phalaenopsis amabilis) wants bright indirect light. Water it every 8 days. Soak the bark thoroughly under the tap once a week, let it drain completely, and never leave water in the pot cover. Silvery-white roots mean thirsty; green roots mean it has had enough. Pot it in no soil at all — coarse orchid bark in a pot with holes. A weak orchid feed with every second watering while in growth, and repot every 1.5 years. Humidity: above 50%. Non-toxic to cats and dogs.

The moth orchid: arching sprays of flat flowers that last for months, on a plant with no bulbs and only a few thick leaves. It is an epiphyte whose silvery-green aerial roots photosynthesise, which is why it is sold in a clear pot and why it must never be planted in compost. The most-sold orchid in the world and by some distance the easiest.

Quick facts

Water: Water every 8 days. Soak the bark thoroughly under the tap once a week, let it drain completely, and never leave water in the pot cover. Silvery-white roots mean thirsty; green roots mean it has had enough.
Light: Bright indirect light.
Humidity: Above 50%.
Soil: No soil at all — coarse orchid bark in a pot with holes.
Feeding: A weak orchid feed with every second watering while in growth.
Repotting: Repot every 1.5 years.
Toxic to pets: Non-toxic to cats and dogs.
Difficulty: Easy.
Mature size: 40–70 cm tall including the flower spike.
Native to: Southeast Asia and northern Australia.

Watering a Moth orchid

Water every 8 days. Soak the bark thoroughly under the tap once a week, let it drain completely, and never leave water in the pot cover. Silvery-white roots mean thirsty; green roots mean it has had enough.

That cadence is the one PlantParlour sets for this species when you name it, and it is deliberately on the cautious side — a plant that asks a day early is safer than one that asks a day late. Log each watering and the reminder moves with the plant rather than with the calendar.

Light

Bright indirect light — an east window, or a metre back from a south one. A moth orchid's leaves should be a mid grass-green; dark forest-green leaves mean too little light, which is the usual reason one never reflowers.

Humidity and temperature

Above 50%. Central heating in winter is what turns a comfortable room into a dry one, and it is the usual reason an established plant suddenly browns at the edges or picks up spider mites.

Soil and potting

Never compost. Phalaenopsis roots are photosynthetic and need air: coarse bark, or sphagnum if you water carefully, in a pot with drainage. The clear pots they are sold in are useful — you can see the roots.

Feeding

A weak orchid feed with every second watering while in growth. Stop feeding in autumn and start again when you see new growth in spring — feeding a plant that isn't growing just builds up salts in the pot.

Repotting

Repot every 1.5 years. Every two years, into fresh bark, after flowering. Old bark breaks down into something that holds water and kills the roots.

Common problems

Never reflowers
Not enough light, or no temperature drop.

Fix: Give it a brighter spot, and a few weeks of nights around 16 °C in autumn — that drop is what triggers a new spike.
Limp wrinkled leaves
Root loss, usually from sitting wet, so the plant cannot drink.

Fix: Unpot it and look: brown hollow roots are dead. Cut them off, repot in fresh bark, keep humidity up while it rebuilds.
Yellowing lowest leaf
Normal — orchids shed the oldest leaf.

Fix: Nothing to do unless several go at once.
The flower spike turning brown after flowering
Finished.

Fix: Cut it off at the base. A green spike can instead be cut just above a node and may branch into a second flush.

Propagation

Occasionally a keiki — a baby plant — forms on an old flower spike. Once it has two or three roots of its own, cut it off with a short piece of spike and pot it up. Otherwise they are not propagated at home.

A cutting taken in PlantParlour keeps its link to the plant it came from, so a propagation years later still traces back to the mother plant — which is the point if you ever sell or trade it.

Toxicity and safety

Non-toxic to cats and dogs.

Questions people ask

How do I get an orchid to flower again?

Keep it in bright indirect light — the leaves should be mid grass-green, not dark — and give it a few weeks of nights around 16 °C in autumn. That temperature drop is what triggers a new spike. After flowering, cut the spike off at the base if it browns, or just above a node if it stays green.

How often do you water a moth orchid?

About once a week: take it to the sink, run water through the bark for a minute, let it drain completely, and put it back. Never leave water sitting in the decorative cover. Silvery-white roots mean it is thirsty; plump green roots mean it has had enough.

Should I cut off my orchid's aerial roots?

No. Those grey-green roots wandering out of the pot are healthy and are doing part of the plant's photosynthesis. Cutting them sets the plant back. Only remove roots that are brown, hollow and papery.

How often should you water a Moth orchid?

Water every 8 days as a starting point — that is the cadence PlantParlour sets for Phalaenopsis amabilis. Soak the bark thoroughly under the tap once a week, let it drain completely, and never leave water in the pot cover. Silvery-white roots mean thirsty; green roots mean it has had enough. Light, pot size and the time of year all move that number, so treat it as a reminder to go and check rather than a rule.

How much light does a Moth orchid need?

Is Moth orchid toxic to cats and dogs?