Phalaenopsis (Moth) Orchids Culture Note

The modern Phalaenopsis hybrids have been developed from Phalaenopsis species that occur in South East Asia. In their natural habitat they grow on trees in tropical rainforests. While still relatively unknown in New Zealand, Phalaenopsis are the most popular orchid in Japan and the USA, due to their suitability as an indoor pot plant. They usually remain in flower for 3 or 4 months, some up to 6 to 8 months.

Growing Phalaenopsis at Home

Phalaenopsis are happiest in the same conditions as people. Large numbers of plants would best be grown in a special hothouse, while individual plants can be successfully grown in the average home.

Light

Phalaenopsis should be grown in filtered light conditions, not in direct sun. The best location is near a window with a northerly aspect. Next best aspects (in order) are North East, North West, East and lastly west. Windows with a Southerly aspect are less suitable. Don’t grow plants too close to the window because they will be burnt by the sun. An alternative is to grow the plants under fluorescent light. They should receive at least 12 hours of fluorescent light per day and be reasonably close to the light. A fluorescent reading lamp may be the answer. Remember – never direct sunlight.

Temperature

Phalaenopsis don’t like to be cold, nor do they like excessive dry heat. The preferred temperature range is 12-28°C. This roughly corresponds to the temperature range people maintain in their home. The plants will survive higher or lower temperatures for variable periods. Windows can greatly magnify heat in summer and be careful of cold draughts in winter.

Humidity

Relative humidity during the daytime should be approximately 70% and at night about 50% because when night temperature drops the relative humidity will increase. The easiest way to provide adequate humidity in a home is to fill a plastic tray with gravel or small rocks and keep a layer of water at the bottom of the tray. The plant should be placed on top of the gravel or stones making sure the bottom of the pot does not come in contact with the water. As the water in the bottom of the tray evaporates the plant will receive that humidity. It is the plant that should get the humidity, and therefore the tray should be approximately the width of the leaf and the length of the leaf spread (from the tip of one leaf to the tip of the opposing leaf).

Air Movement

Good air movement will prevent fungus and spores from settling on the plant and will also prevent spotting on the flowers due to high humidity. Good cross ventilation is sufficient. In a hothouse, it is important to have air movement 24 hours per day.

Watering

The successful growth of Phalaenopsis relies on keeping the roots moist and the leaves dry. When watering, just water the pot and let the water drain into the tray/saucer. Avoid water entering the crown of the plant (the crown is the central point from which the leaves grow). Water in the morning to allow for any water that is collected in the crown to evaporate. Remember to keep the potting mix moist but not continually wet. In summer, the plant may need to be water 2-3 times per week and as little as once per week in winter.

Fertiliser

Any soluble fertiliser is suitable as long as it is well diluted. It may be best to use half the recommended strength. Alternatively, use a weak solution on a weekly basis. We recommend ‘ORCHIDFEED FERTILISER 2.1.2 from September till Feb, then switch 2.1.4 from February to August’ as a fertiliser.

Repotting

This usually only needs to be done when a plant has outgrown its pot or the potting mix has deteriorated. A large plant can be grown in a small pot. We use our PRIME ORCHID MIX. The main requirement in a mix is that it is free draining and open.

The reward for doing things correctly is a plant that will be flowering for three months or more. The main flowering time is spring but large plants may flower more than once per year.