Name: moth orchid, Phalaenopsis spp and varieties.
Height: up to 30cm; flower spikes much taller.
Foliage: broad, mid-green, leathery/fleshy.
Climate: sub-tropical to tropical; indoor plant in temperate and colder areas.
Soil: open, free-draining commercial orchid bark (8–18mm particle size preferred).
Position: good ambient light; avoid direct sun through glass indoors.
Flowering: exotic five-petalled blooms ranging in colour from pure white through to deep cerise and variations.
Feeding: use a long-term controlled-release fertiliser supplemented with liquid food every 4–6 weeks.
Watering: keep bark moist but not wet; empty saucers under pots.
Phalaenopsis orchids feature flowers ranging in colour from palest green and pure white through to soft pink, deep cerise and also bi-colours including white or mauve with dark brown-red striping. Its broad, dark green leaves have a fleshy appearance, and its thick roots are often exposed on the surface of the pot.
Like many tropical orchids, Phalaenopsis is an epiphyte—that is, it grows on a tree or rock rather than in the ground. In nature, phalaenopsis is found in the forks of trees and on branches or rocks. Its roots grow into crevices to anchor it and to find moisture and food.
To successfully grow an orchid it is important to mimic its natural growing environment. The moth orchid should not be potted into a standard potting mix. Always use a specialist orchid mix containing medium to coarse bark (8–18mm screened pine bark chips) and plant into a squat pot that is slightly wider in diameter than the root ball and no more than 150–175mm deep.
The pot may be clay, ceramic or plastic and must have a good-sized drainage hole in the base. Fill the pot to within 50–60mm of the rim with bark, place the plant in the centre, arranging its roots out and slightly downwards, then lightly cover them with bark. The plant may be a little wobbly in the pot to start with, but that is fine—its roots will grow to anchor it more firmly over the following months.
Moth orchids need good light. Do not place a pot on a sunny windowsill, because the direct sun through the glass will burn its leaves. A light curtain between the plant and the glass will reduce the sun’s intensity.
The perfect growing position is on a table or bench close to an east- or north-facing window where the plant will get good ambient light for at least six hours a day.
Warmth is essential, especially during a southern winter, but do not place pots near heating or air-conditioning outlets—hot, dry air or draughts will damage the plant. Contrary to popular belief, the bathroom is not the ideal location for a moth orchid! It is often too cold, and the light too muted.
In warm temperate to sub-tropical climates, plants will thrive on a sheltered outdoor verandah or in a shade house.
How often you water your plant will depend on the weather at the time and where the plant is growing.
Water about once a week, thoroughly wetting the bark right through to the bottom of the pot. Excess water should flow out freely through the drainage hole. Don’t leave the pot standing in water—empty the saucer when the pot has drained.
When the weather is hot and humidity is low, you will need to water more often—every three or four days. In the cooler months you will only need to water every 10 days or so. Be guided by the appearance of the plant’s leaves. If they look soft or slightly wrinkled, they are dry and the plant needs water.
Premium-quality bagged orchid barks usually contain some controlled-release fertiliser that will provide enough food for the plant for up to six months. However, your orchid will also respond well to extra fertiliser during the peak growing season and while it is producing flower spikes.
A liquid or water-soluble plant food for potted plants, used as directed on the label, will give your plant an added boost. Apply every four to six weeks. Top up the controlled-release fertiliser every six months with one suitable for potted plants.
Moth orchids often flower twice a year, and the flowers last for several months at a time. The flower spike should not be cut off after the first flush of flowers! Trim it back to the lowest node (“knob” or joint on the stem) to encourage the spike to send up a new shoot that will flower.
Moth orchids are reasonably pest-free, but occasionally outdoor plants may be attacked by aphids and other sap-sucking insects. A pyrethrum spray every two or three weeks will control them.
If the leaves of the plant develop black spots or stripes, the culprit is likely to be a virus disease. There is no treatment for virus-affected plants, so discard the plant before the infection transfers to other healthy plants.
Browning of leaf tips is most often caused by water—either too much or too little—so adjust your watering program. Leaves turning yellow, especially the lower ones, indicate that they are old and are preparing to die and drop. This is nothing to be alarmed about, as long as the rest of the plant looks healthy!
Peace lily (Spathiphyllum): a hardy indoor plant with glossy green leaves and white flowers.
Anthurium: indoor plant with deep green leaves and flowers from creamy white to deep purple-red.
Maidenhair fern: delicate bright-green fronds on fine black stems; maidenhair fern provides excellent contrast to bold orchids.
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