Why Plants Die
Theme
Theme

Moth orchid

Phalaenopsis, Orchidaceae

Sources last read 14 September 2026.

Difficult One of the harder ones, and one of the reasons the diagnosis tool exists.

Also called Moon Orchid, Moon Orchids, Moth Orchids, moth plant, Phalaenopsis Orchid and Phalaenopsis Orchids.

Moth orchid (Phalaenopsis), the whole plant.
Julian Herzog ( Website ), CC BY 4.0 · Wikimedia Commons

Toxicity is partly unassessed

  • Listed as non-toxic to cats by ASPCA.
  • Listed as non-toxic to dogs by ASPCA.
  • Not assessed for people. RHS publishes no harm statement for this plant. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.

What the sources say about its care

Sources file this plant under other names: Phalaenopsis sp. (ASPCA, genus only). Citations below point at the name its source uses.

Light
Partial shade
RHS · read 11 September 2026
Water
Well-drained
RHS · read 11 September 2026
Humidity

No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.

ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%
Penn State Extension · read 11 September 2026
Temperature

How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.

H1A — warmer than 15°C 15 °C
RHS · read 11 September 2026
Toxic to cats
Listed as non-toxic
ASPCA names the genus (Phalaenopsis sp.), not the species.
ASPCA, filed as Phalaenopsis sp. · read 11 September 2026
Toxic to dogs
Listed as non-toxic
ASPCA names the genus (Phalaenopsis sp.), not the species.
ASPCA, filed as Phalaenopsis sp. · read 11 September 2026
Harmful to people
No harm statement is published for this plant; that absence is not evidence it is safe.
RHS · read 11 September 2026

How it usually goes wrong

Crisp margins that appear in winter

On a moth orchid the browning starts furthest from the midrib and works inward, and it crumbles rather than smears. The centre of each leaf is untouched.

Leaf margins are the end of the water supply, so they are the first tissue to run short when the air takes more than the roots can send. Penn State Extension cites 30% to 60% as the recommended indoor range, and a heated room in winter sits below it.

Telling it apart: When it started. Edges that browned as the heating came on point at air; edges that browned through a wet summer do not.

Penn State ExtensionMoth orchid brown leaf tips and edges: causes
Growth slows and what does arrive is thin

The newest leaves on the moth orchid are the palest and smallest, and the stems carrying them bend toward the brightest side of the room.

A plant stretches when the light is short of what it evolved for. Its source describes partial shade, and a room darker than that sets the crown reaching.

Telling it apart: Compare the colour of the newest leaf with one grown last year. Paler and smaller together is light; paler at the same size is more often feeding.

RHSMoth orchid leggy, leaning growth: causes
The whole crown sags between waterings

The moth orchid hangs evenly all over, and the compost has gone pale and hard. Nothing is spotted or rotten; the plant is simply short of water.

Stored water is spent before the plant gives up anything else, and the tissue creases as it empties. Its source describes well-drained soil, which assumes the store is refilled.

Telling it apart: Lift the pot. A plant that is light and sagging is thirsty; one that is heavy and sagging is not.

RHSMoth orchid drooping or wilting: causes

Not sure which it is? Ask the diagnosis questions for Moth orchid.

Routine care

Watering
Water orchids in the morning with lukewarm water: set them in a sink and let water run freely through the foliage and potting medium. Let the pot drain fully so the plants are not left sitting in water.
NC State Extension · read 13 September 2026
Mist the aerial roots regularly, and water once the plant is nearly dry; roots turning pale and silvery show that watering is due.
RHS · read 13 September 2026
Feeding
Feed regularly with balanced fertilizer, either at half strength twice a month or at quarter strength every week. Bud blast (flower buds dropping) can result from shifts in location, fertilizer, moisture, humidity or temperature.
NC State Extension · read 13 September 2026
Through the season, orchid fertiliser can be given at regular intervals.
RHS · read 13 September 2026
Repotting
Such plants do better moved into a bark-based orchid mix. Repot orchids roughly every two years, once flowering has finished or when new leaves start to show.
NC State Extension · read 13 September 2026
Propagation
Growing from seed is possible only under controlled laboratory conditions. Mature plants can form sideshoots (keiki); once their new roots are 2cm or longer, detach them and pot each on its own in orchid propagation mix.
RHS · read 13 September 2026
Pruning
Pruning is not needed. Shorten a flowered stem to a lower node to promote more flowers.
RHS · read 13 September 2026
Pests and diseases
Can be troubled by greenhouse thrips and other thrips, hemispherical scale and Boisduval scale. Diseases: botrytis blight.
NC State Extension · read 13 September 2026
Can be troubled by scale insects, aphids and mealybugs. Diseases: usually none. To prevent bacterial rots, keep water out of the centre of the leaf crown.
RHS · read 13 September 2026

Move something and watch

Loading the simulator. It needs JavaScript; the care table above does not.

Flowers of Moth orchid (Phalaenopsis).
FlowersAgnes Monkelbaan, CC BY-SA 4.0 · Wikimedia Commons
Moth orchid (Phalaenopsis) growing in a pot.
In a potWildfeuer, CC BY-SA 3.0 · Wikimedia Commons

About the plant

Phalaenopsis, also known as moth orchids, is a genus of about seventy species of plants in the family Orchidaceae. Orchids in this genus are monopodial epiphytes or lithophytes with long, coarse roots, short, leafy stems and long-lasting, flat flowers arranged in a flowering stem that often branches near the end. Orchids in this genus are native to Asia, New Guinea, and Australia, but mostly occur in Indonesia and the Philippines.

From Wikipedia, CC BY-SA 4.0 · read 13 September 2026

Native range
Tropical & Subtropical Asia, NE. Australia
NC State Extension · read 13 September 2026
Growth form
Epiphyte; habit erect
NC State Extension · read 13 September 2026
Columnar upright (evergreen)
RHS · read 13 September 2026
Size
Height 18–24 in; width 6–24 in
NC State Extension · read 13 September 2026
Height 0.1-0.5 metres; spread 0.1-0.5 metres after 2–5 years
RHS · read 13 September 2026
Flowering
Flowers gold/yellow, green, orange, pink, purple/lavender, variegated, white
NC State Extension · read 13 September 2026
Flowers pink in spring, summer, autumn and winter; purple in spring, summer, autumn and winter; white in spring, summer, autumn and winter; yellow in spring, summer, autumn and winter
RHS · read 13 September 2026

Common problems with Moth orchid

Other Phalaenopsis

More of the Orchidaceae family

Plants with similar care

Sources

What this does not cover

The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.

Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.

If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.