Growing Phalaenopsis

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Phalaenopsis are fast becoming recognised as the most beautiful flowers in horticulture. The plants are also one of the fastest growers in the orchid family. Their long arching sprays of long lasting blooms are very popular both on the showbench and for floral arrangements and bridal bouquets. The plants and blooms may be a little more expensive than others because commercial production on a large scale usually entails heating in Winter and fan forced ventilation. Breeders are now producing a wider range of colours. Whites are still the most popular with showbench blooms reaching over 5 inches in diameter.

Mature plants can bloom from mid winter through to December if the spike is cut just above the third then the second live node from the bottom of the flower stem to produce a second and third flowering.

Warning: If the leaves go limp, cut off all blooms and spikes at the base immediately!

Although species Phalaenopsis mostly come from warm humid areas of the Philippines and surrounding islands, one is native to Australia, and others come from New Guinea and South East Asia.

Like most orchids they can be grown under a wide variety of situations if a few special conditions are met. It is therefore important (as with all orchids) to ask your nurseryman for relative cultural advice.

Phalaenopsis grow well under approximately the same conditions as African violets. So if you can grow African violets, you can grow Phalaenopsis.


TEMPERATURE RANGE: - Minimum of 15C at night up to 30oC in daytime, except in Autumn (February, March and April) when they should be allowed to drop to 12oC at night for a few weeks to help initiate flower spikes.

After this, care should be taken to ensure a minimum nighttime temperature of 15C for the rest of Winter. Although they are warm growers, above 30C, they tend to stop growing, so if this is likely take steps to reduce the temperature by improving ventilation or misting the floor, etc.

LIGHT: In nature Phalaenopsis come from very shady locations in rainforest, so about 80% to 90% of shade is ideal (i.e. about 10% to 20% filtered direct sunlight). The extra light (20%) is given at spiking time in Autumn.

N.B.: This is filtered direct sunlight and NOT incident light coming from a side window. When the shadow of your hand is barely discernible, that is 10% sunlight. Generally, if leaves are a very dark green, that denotes too much shade (be sure excessive nitrogen in fertiliser is not the cause). If leaves are yellowish green, that denotes too much sun. Leaves should be firm and mid-green colour.

WATERING: These plants should NEVER dry right out, (unlike many other orchids) but should not be kept too wet either. Best to pot water if you can. If you must water overhead, tilt plants on an angle so that water does not lie in the crown. Water before 10 a.m., but only on fine, sunny days. Then let the leaves dry out for night. Remember cooler air at night deposits water on plants as it can't hold as much moisture as warm air. On a cold Winter morning, if you don't like a bucket of cold water thrown over you, don't do it to your plants: Wait till the water warms up to room temperature. Cold water on a spiking plant will drop buds.

DEHYDRATION: - Can be caused by not enough water, as well as too much water, as too much water rots roots so the plant cannot take it up.

HUMIDITY: - Should be fairly high as the leaves like to be in moist air in the daytime (about 80%). It is not sufficient to water the pot, the moisture should be in the air. At night, humidity should be a lot lower or bacterial rot will result. In dry locations we can increase humidity around the plant by placing it on top of a tray of moist pebbles. (NOTE: The base of the pot must NOT be in water). Most air conditioning dries the air, so plants should not be left too long in this situation.

VENTILATION: - Plants should not be left in stagnant air, as bacteria and fungus spores can infect. Soft watery bacterial rot is the usual result of inadequate ventilation. To treat, cut off the affected part of the leaf, treat the cut end with Mancozeb, then let it dry before spraying with a sanitiser such as Benzylkonium Chloride to kill spores around the plant and benches. THEN improve ventilation to remove the cause. While you are treating plants, keep a little on the dry side for a while. If you cannot improve the natural ventilation, fans should be used constantly to reduce temperature on hot days and to dry plants out for cold nights.

TYPE AND SIZE OF POTS: - We prefer a well drained pot with a dome in the base to prevent retention of water, and to give a good air flow through the pot and over roots.

Plastic pots are ideal for situations that dry out quickly, whereas Terra cotta pots are ideal for areas of high humidity and little natural breeze.

Choose a size of pot that will comfortably hold the root system. Try not to overpot as this will affect drying out time and moisture levels in the pot.

COMPOST: - For larger plants in 5 inch, 7 inch, and 10 inch pots we use our 5" grade premium sterilised and treated bark with about 20% good quality hardwood charcoal. Also about l" of finer 4" grade on the top to provide more moisture for the roots.

Smaller grades are suitable for smaller plants in smaller pots. Again, the pot should just comfortably hold the root system. If the mix you are using dries out too quickly, use a grade finer mix. If the mix you are using stays too wet, use a grade coarser mix. Do not use a mix too fine as it tends to stay too wet and does not allow good airflow over the roots. (Causes root rot).

WHERE TO GROW THEM: - Ideally in a glass house or similar structure with adequate vents at top and bottom (not just in the side). Shadecloth and wire netting hail guard should be about 2 ft. ABOVE the roof to COOL AND SHADE in Summer. Some form of heating BELOW THE BENCH IN Winter is essential if growing on a large scale. Gases from Kerosene or LP gas heaters should not be allowed inside.

At night, especially in Winter flowering time, humidity should be kept lower to avoid spotting blooms. This of course is the IDEAL GROWING ENVIRONMENT!

Other less than ideal situations can also be successful.

When cold, plants can be taken from the shadehouse (80% to 90% shade) into a laundry or house just for the night. The top of the hot water system, if it is in the laundry, is ideal. House environment is usually dry and warm enough for nights.

They can also be grown permanently inside the house as a house plant on an ENCLOSED verandah, patio or sunroom, preferably on the north side, provided some form of humidifying is used. (A tray of moist pebbles. See section on Humidity.) 10% filtered direct sunlight is essential, so near a window with a curtain giving this shading is OK. THE KITCHEN OR BATHROOM IS NOT SUITABLE IF GAS OR KEROSENE APPLIANCES ARE USED. (Phalaenopsis are very susceptible to air pollution).

FERTILISING: - If you have the time, plants like fertilising at strength with every watering, but most growers seem to settle for twice each week at strength. They need fertilising more often because they have no bulb or cane to store food. These plants are just 5 or 6 leaves with 5 or 6 roots. Do use a good quality horticultural wetting agent when fertilising as well as spraying. This breaks down the surface tension and allows 100% of leaves to wet, as well as allowing the bark to absorb food, so the plant is CONTINUALLY fertilised.

Our FLOWER BOOSTER N-6.9%, P-10.8%, K-27.1% is ideal for autumn, (February, March and April). The low N. gives some leaf growth. The P. gives good new root growth and the K. gives HARD growth as well as initiating flower spikes.

AQUA K. N-13.7%, P-4.6%, K-22.5%. This formula gives good hard growth from May through to about October.

AQUA FEED. N-20.3%, P-3.3%, K-17%. This formula is good to boost cell growth when necessary from about October to February, but growth will be soft if used for too long. (Change to AQUA-K. if this happens).

Note: All these 3 fertilisers are totally soluble (no undissolved salts) and contain chelated trace elements. (N.B. - Do not water or fertilise on cloudy days.)

REPOTTING:- Repot (1) When the mix has broken down (our mix does not).
(2) When the plant has grown out of the pot.

Best time to repot is after flowering, but well before the autumn growing time, preferably November. When potting, cut or break the base of the stem off and check there is no black marks. If there is, keep cutting until the cut is a clean creamy green colour.

Cut off any roots that are not solid and soak the plants and roots in a standard Mancozeb solution for 10 minutes. Remove, - then seal the bottom of the stem with a thick paste of Mancozeb or Thiram. Allow the plant to dry before repotting.

N.B.:- Make sure your cutters are sterilised to prevent spread of disease, especially virus. (These are spread by sap contact). See our Lecture Notes on repotting for details.

FLOWERING TIME:- Stake spikes early to give a nice arching spray. Once a spike has started DO NOT MOVE OR TURN THE PLANT, or the spike will bend, as spikes and blooms grow and open towards maximum light (North). So make sure any side, or reflected back light is kept to an absolute minimum. As buds form and blooms open, the weight on the spike increases, so it may need extra staking.

This is the danger time for Botritis spotting of blooms (due to high humidity when cold), so warm the air a little and ventilate with fans, especially on dull days and at night. Increased light intensity combined with a high potash fertiliser at this time will harden up the spikes.

AIR POLLUTION: - Phalaenopsis are very susceptible to air pollution, especially when flowering. You should avoid smoke from fires, kerosene drop out from planes near an airport, car exhaust fumes, aerial spraying for insects, weeds, etc. All these will affect the growth of plants, as well as cause bud drop. Dust should be wiped or washed off leaves in dusty locations.

INSECTS: - to watch for are:
MITES spray with Kelthane
SLUGS & SNAILS spray with Measurol or Metaldehyde
MEALYBUG spray with Clear White Oil and Rogor
SCALE spray with Clear White Oil and Rogor
APHIDS spray with Diazinon

All sprays should have a good horticultural wetting agent added if White Oil is not used!


Cut off affected part of leaf and treat cut with MANCOZED or THIRAM.
Improve ventilation, keep plants drier for a while.
Sanitise plants and surrounds with BENZYLKONIUM CHLORIDE. - Remove all old leaves and rotting vegetable matter.
Do not leave it in a bin on the floor, as this harbours spores.
Note: - Benzylkonium Chloride will also kill green algae on the top of the compost and elsewhere.
Reduce watering
Use a coarser grade of mix to increase airflow over the root system.
(See notes on Ventilation, Watering and Compost).
Note: FOSJECT should not be mixed with any compound containing copper. (Best to use it on its own).


This article courtesy of

Sunshine.gif (14500 bytes)

Sunshine Orchid Nursery

Wholesale & Retail
Import & Export

2034 Roghan Road,
Bald Hills,
Queensland, Australia, 4036.

Phone (07) 3263 4902



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