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Moth orchids

With increasing popularity, the moth orchid flaunts its exotic beauty at home gardeners.

The moth orchid — or Phalaenopsis — is becoming increasingly popular and it's one of the best orchids for beginners to grow. Take a look at our guide below to keep your phal blooming happily for months.


Moth orchid Phalaenopsis are tropical plants so their first requirement is a warm room.

When in flower, temperatures should remain above 16 degrees C, although they can endure temperatures as low as 12 degrees for brief periods. The very occasional fall to around 10 degrees will not harm your plant, but anything below this may damage young leaves. An ideal temperature is around 22-24 degrees — moth orchids thrive in consistently warm areas — although 16-24 degrees is probably more realistic. Higher temperatures, up to 35 degrees, are tolerated if humidity is not too low. If leaves turn yellow, it is likely that they have suffered low temperatures.

Moth orchidTo initiate flower spikes, usually in autumn, a brief period of temperatures below 16 degrees are necessary. About three weeks of night-time temperatures at about 11 or 12 degrees will ensure good bud initiation.


Phals like humidity. Their succulent leaves store water, and if the air is constantly dry, this water will evaporate and leaves may wilt. Air conditioning, dehumidifiers, heaters and even soft furnishing absorb moisture from the air, effectively lowering the humidity level.

You can increase humidity by sitting your plant on a saucer of pebbles with water, ensuring the plant does not touch the water. Misting will also create humidity, but make sure the plant has time to dry out before nightfall.

Moth orchidLIGHT

Your plant should NOT be placed in direct sunlight or the leaves will burn. In their natural habitat, phals grow in the shade of the forest canopy. Too much light and their dark green leaves may suffer heat damage and begin to fade. Too little light and the plant may not flower and foliage may go limp. Warm, humid, circulating air will help keep the leaves cool. If the light is bright and humidity is low, the leaves may shrivel.
Place near an east, west or shaded south window.


A sure-fire way to kill your plant is to let it sit in water. The water will crowd out the air around the roots and suffocate it. On the other hand, you should not let your plant dry out.  Phals grow naturally where the sun shines in the morning, the rain falls in the afternoon and the sky clears before sunset. This explains their need for frequent watering, and because they mostly grow in trees (being, for the most part, epiphytic), drainage must be good.

Moth orchidWater thoroughly under a tap with tepid water, and do so in the morning. Leave to drain and ensure no water remains on the leaf base, particularly in cooler weather, or rot may develop. Aerial roots can also be sprayed to take in water. In cooler weather, you can water less frequently, although you will still need to ensure your plant does not dry out.


Moth orchidLittle and often is the key to feeding (once a week is good) and a soluble fertiliser (I use Watkins Bounty fertiliser at half strength), given at the time of watering, is ideal. Flush the plant thoroughly with clear water before feeding. There are a number of orchid foods available on the market that you can use; whichever brand you choose, dilute and use as specified.

Foliar feeding is also beneficial. If you use this method, dilute about half the strength used for pot feeding, then mist spray onto the foliage.

Note: Orchids will do far better with too little fertiliser than with too much.


Moth orchidAlthough flowers mostly appear in winter and spring, spikes can appear at any time of the year. It takes about three months from the time the spike develops to the time it flowers. After flowering, if you leave the spike, more flowers can develop, although it can look a bit untidy in the meantime and flowers are generally smaller. If you cut off the spike just above the second node from the base, another spike may emerge. However, some believe it best to remove the spike entirely after its main flowering to allow the plant to invest its strength in the following year's flowering.


Moth orchidOnly repot when the plant is growing out of its pot. This does not mean when you see roots at the top of your pot; some roots have a tendency to wander and do not like being forced back inside. These aerial roots should be left as is.

Mature plants may need the potting medium replaced every two years; gently lift out old medium and replace with the new material, working it very carefully around the roots. You must use a free-draining mix. Bark is generally used, mixed with pumice, sphagnum moss, polystyrene, foam or similar material.

If you find you do need a bigger pot, aim for as little root disturbance as possible. The best time to repot is spring or summer.


Mealy bug and scale can be controlled with Orthene. Spray outside, early in the day.

Leaf rot is caused when water is left to sit on the leaves overnight. Cut out any sign of leaf rot immediately and apply a protective fungicide to ensure no further spreading.

Jane Wrigglesworth

Reproduced with permission from NZOOM Home and Garden content,
from the previous website of  TVNZ News

The views expressed here are not necessarily those of the RNZIH

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Last updated: March 1, 2021