Moth Orchid

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An east windowsill is its natural home; it also gets by in bright shade, kept out of direct afternoon sun. Tucked too far into shadow, it may keep its leaves but skip its next bloom.

In the wild, moth orchids cling to trees in the shade of warm, humid forests (Penn State Extension), and on Borneo most species grow toward the base of the trunk, in low light (Kew). One Bornean cousin, P. pantherina, lives high in the canopy in bright, diffuse light (Kew).

Indoors, an east window is the classic spot (NC State, Clemson). A west window works as well, and a south one with some success (Penn State), as long as the sun is filtered or kept off the leaves, since summer sun can scorch them (RHS).

Growing it under a lamp? Leave headroom: the flower spike climbs as it buds and may end up brushing the bulbs (Penn State).

Picture the light on a shaded tree trunk, steady and soft, with a little morning sun at most, and give it the closest match you have.

About every 7 days in summer and every 7-10 in winter, with the bark drying partway between, not all the way through. Running a day or two behind bothers it less than bark kept wet, which smothers its thick roots.

Chunky bark is its usual potting mix, a stand-in for the trees its roots grip in the wild (Penn State). When you repot, NC State suggests a bark-based orchid mix.

Bark holds little food of its own, so NC State suggests a balanced fertilizer at quarter strength every week, or half strength twice a month.

In dry winter air, a bud or two may drop before opening (Penn State); if that bothers you, a more humid room may help.

Gone for a while? Two weeks is fine if it gets a good soak and a full drain the day you leave.

Slow-growing broad leaves stay low and close to the pot while the flower spike carries it to 1-2 feet. When the last bloom drops, cut the spike above a node below the lowest flower; it may branch and bloom again.

It grows from one short, central stem, adding leaves in two opposite rows (plant patents call this monopodial growth); the wild Phalaenopsis amabilis usually holds just 3-5 (Kew). Thick, fleshy roots grow from the lower stem (Kew).

About every two years, NC State suggests repotting into fresh bark, since the old mix breaks down around those roots.

Now and then a small offshoot sprouts low on the spike, and it can be detached and potted on its own (plant patent).

In bloom it leans its flowers out to one side, so give it clear air there: the end of a windowsill, or a shelf edge where the blooms can hang past.

The ASPCA lists moth orchids as non-toxic to dogs and cats, and NC State tags them the same. For kids, Connecticut’s poison control center lists orchids as safe.

Any plant can upset a stomach that isn’t used to it; for a moth orchid, that’s the whole of it.

If a toddler gets a taste and anything worries you, Poison Control is there to ask.

Here it’s the plant that needs protecting. A cat that bats at dangling things may snap a spike long before it ever gets sick, so set it where the blooms sit beyond paw’s reach, and enjoy it with a pet-⁠safe set-⁠up.

1. ASPCA: safe for dogs.
2. ASPCA: safe for cats.
3. UConn Health: safe for kids.

Cats and dogs: The ASPCA lists it as non-⁠toxic.

Kids: No poison-centre listing; rated from university extension sources.

Keep it at 60-85°F. Keep it away from cold glass in winter. It likes 50-70% humidity and gets by at 30%.

Temperature

60-85°F

Humidity

50-70%

Scale tucks along the underside of the leaf midrib and under the leaf sheaths. Mealybugs wait in leaf axil crevices, at the base, and on flowers. Thrips (flowers, foliage) and mites (leaf undersides) are occasional.

• Scale
• Mealybugs
• Thrips
• Spider mites / false spider mites

Not many. Scale and mealybugs are the usual pests, with thrips and spider mites now and then; rot is the real danger (NC State, UConn).

Scale looks like small brown or tan bumps stuck to the leaves, often underneath; mealybugs look like tufts of white cotton where the leaves meet. Wipe them off with a cotton swab dipped in rubbing alcohol, then check again next week; if they come back, insecticidal soap is the next step.

Spider mites leave pale speckles and fine webbing under the leaves; thrips leave silvery streaks on leaves and flowers. Rinse the plant in the sink, undersides included, then follow up with insecticidal soap.

Rot shows as a leaf going soft, yellow, or black at the base, usually after water sat in the crown or the bark stayed soggy. Cut the soft leaf off, keep water out of the crown, and let the pot drain well from then on. Brown spots on the flowers are a fungus called botrytis (NC State): pick those flowers off and keep water off the blooms.

Feed at half strength twice a month, lighter in winter, and run clear water through the pot monthly. Stake the new spike in winter, cut it after the last bloom, and repot in spring or summer every 2 years.

• Feed24× a year
• Flush salts12× a year
• Stake1× a year
• Deadhead1× a year
• Cool nights to trigger spike1× a year
• Repot1× a year

Orchid bark in a pot with plenty of drainage holes, never ordinary potting soil: in the wild its roots cling to trees, and they need air.

Repot every two years, into fresh bark, once it has finished blooming and never while it’s in flower (Clemson Extension). A few roots climbing out over the rim is normal; a pot packed solid with roots means it’s time.

Feed it a balanced fertilizer at half strength twice a month, or at quarter strength weekly, from spring into early fall (NC State, Clemson).

Each wide, deep green leaf has a waxy gloss, as if polished. The plant is open rather than bushy, with leaves low and soil showing between the stems.