Moth orchid

About Moth orchid

Moth orchids are epiphytes from tropical Asia and northern Australia that hold a few thick leaves and send up an arching spike of flat, moth-shaped flowers that last four months or more (NC State). They are the easiest orchid for a windowsill: they take the lowest light of the common orchids, sit happily in bark at room temperature, and with a cool spell in fall most bloom once a year. More than 34,000 hybrids are registered, in white, pink, yellow, peach and spotted patterns; the blue ones are dyed.

Hardy outdoors only in zones 10-12 (NC State); it is grown indoors everywhere and can summer outdoors in shade once nights stay above 55 F, coming back in when evenings drop into the 50s (Clemson, UMD).

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Almost always bought as a blooming nursery plant in bark or moss; home propagation isn't covered by the Extension pages we opened.

Growing it indoors

• Light: An east window is ideal, or a well-shaded west or south window; light-green leaves mean the light is right, dark stiff leaves mean too little, and yellowish leaves with red edges mean too much, since direct sun burns them (NC State, UMD).
• Water: In the morning, run tepid water through the bark for a minute or dunk the pot, then let it drain completely; mature plants need this about once a week, more in summer heat and less in winter, when the bark has dried somewhat and the pot feels light (NC State, Clemson, UMD). Never let it sit in water; soggy roots rot, and ice cubes and misting are no substitute for a proper soak.
• Humidity: Iowa State aims for 40-60 percent humidity; set the pot on a tray of wet pebbles with the pot bottom above the water, or run a humidifier, since wrinkled leaves and dropped buds follow dry winter air.
• Temperature: Keep it above 55 F (Iowa State; Penn State gives 60 F nights as the minimum), at normal 65-80 F room temperatures, off cold winter glass and away from drafts and heat vents; a fall drop to 55-60 F nights for a few weeks triggers the flower spike (NC State, Iowa State, Clemson).
• Feeding: A balanced orchid or houseplant fertilizer at half strength twice a month, or quarter strength weekly, in spring and summer; UMD feeds every third or fourth watering and skips winter (NC State, UMD).
• Repotting: Every 1-2 years, when the bark has broken down or new leaves and roots are starting, into fresh bark in the same size pot or one barely larger; never repot while it is in bloom (UMD, NC State, Clemson).

Soil

A bark-based orchid mix in a pot with excellent drainage; plants sold in pure sphagnum moss are hard to rewet and are best moved into bark at the next repotting (NC State, Iowa State).

Pot in a bark-based orchid mix in a pot with excellent drainage (NC State, Iowa State).

Feeding

• Spring and summer, while leaves and roots are growing: balanced orchid or houseplant fertilizer, diluted. Half strength twice a month or quarter strength weekly (NC State), or every third or fourth watering (UMD); water first, and wait several weeks after repotting before feeding again (UF/IFAS).
• Fall and winter, during bud set and bloom: none, or a light feeding. UMD skips winter feeding; Clemson keeps feeding lightly through the rest period from mid-spring to early fall only.

Overfeeding gives leaves at the expense of flowers, and letting the pot stand in water rots the roots (UMD, Iowa State).

Harvest

Blooms about once a year with good care, usually winter into spring after cool fall nights, and the flowers last four months or more (NC State). When the last flower drops, cut the spike just above the first node below the faded flowers for a chance at a side branch, or cut a yellowed spike back near the base (NC State, UMD).

Varieties (2)

NC State names two wild species but no cultivars; the tens of thousands of registered hybrids are sold by color rather than by name.

Pests to watch for

Scale insects, Mealybugs, Thrips

Diseases and problems

Root and crown rot, Gray mold (Botrytis), Bud blast, Orchid viruses

In the kitchen

Safety: Not listed as poisonous to people or pets (NC State, ASPCA).

Pets: Non-toxic to dogs, cats and horses (ASPCA, listed as Phalaenopsis sp.).