Without knowing where you are and the name of the Phalaenopsis orchids it is very difficult to answer your question. The Phalaenopsis Hybrid ancestors come from different but mostly warm climates, so you will get some that are vigorous in your conditions, others that just limp along.

Thank you. I'm not sure of the name of the phal sorry but its large white flowered if that helps? I expect its a very common white flower version as there are numerous for sale around the area. Also, I am in Newcastle, Australia (not too far from Sydney) :)

The paradox might be that if you lived in a centrally heated home somewhere in Northern USA you might find Phalaenopsis easy to grow. Here, even orchid society members grow other types of orchids. All you can do is research and try this or that method. After many years of trying I have only had moderate success with them.

Here are some culture notes for Sydney, that might lead to answer.

Phalaenopsis Culture

These notes relate to Phalaenopsis culture in the Sydney area. These orchids cannot be grown outside in the yard or in a shade-house because winter minimum temperatures are too low and some summer maximum temperatures are too high. These temperature problems plus low humidity mean that special housing to meet Phalaenopsis needs is required, or the plants should be grown inside your home.

Culture within the home

Finding the right place to put the plant. Your plant needs bright light, humidity levels of about 60% and temperatures where both you and the plant will be comfortable. That rules out one place that is often suggested, the bathroom. Another place that is not good is one of those small closed in sunrooms where dry winter air is heated and the humidity levels are too low. My plants are on the windowsill of a large airy kitchen. Winter temperatures range from 12C to 18C each day and a fibreglass blind protects the plants from all but a few hours of gentle sun in winter. Do not expose the plant to harsh direct sunlight because the leaves of the plant will burn. Early morning sun is best, but late afternoon sun is also OK provided it is screened as described above.

Humidity

Some people recommend spraying the plants with water every day to raise humidity. This is not necessary because the humidity level in most homes is about 60%. You may wish to place the plant on a humidity tray containing pebbles and water. This is not necessary either, but will not cause harm, provided the bottom of the pot is not sitting in water.

Watering

Frequency depends on the potting material and the atmosphere in the house but as a general guide once a week in winter grading to two or three times a week in summer. Potting material should be kept moist but not sopping wet. Make sure no water is left sitting in the crown of the plant for an extended period, as the plant may rot. Use a tissue to soak up excess water.

Fertilizing

Use complete liquid fertilizer with every third watering, but only at half the prescribed strength. Wet the foliage as well.

Repotting

Every two years in late spring. Use specially prepared orchid bark, not Cymbidium mix. Try not to disturb the roots too much and just replace some of the older bark. Do not be in hurry to put the plant in a larger pot, because like most orchids, the plants seem to do better in a slightly pot-bound condition. Do not worry about some roots growing outside the pot. That is a good sign.

Treatment of flowering stem

When the flowers are nearly finished, you can cut the stem off just below the lowest flower and the plant may produce a new flowering shoot from the node just below the cut. BUT, note that most experienced growers cut the stem off at the base so the plant will put all its energy into growing new leaves, and therefore will produce better flowers next time.

Making the plant flower

The plant should produce a new flowering stem in late autumn as the temperatures drop. Some growers induce flowering by watering the plant with Epsom salts (Magnesium Sulfate) once a week several times in autumn. The amount of Epsom salts required is one tablespoon full in a bucket of water.

Pests and diseases

Your plant should remain pest and disease free in the home environment. Fungal disease which shows up as black spots on the leaves is a symptom of over-watering. Cut back on the watering a bit and seek help from a nursery orgarden centre if the problem persists. Phalaenopsis are also susceptible to mealy bugs, which are small, white, fluffy looking bugs that live on the undersides of leaves or between the leaf bracts on the central stem. Use either White Oil or Pyrethrum to remove these pests. More than one application may be required, so if you see another bug, spray again. If you use White Oil, make sure to move the plant out of direct sunlight for a few days otherwise the leaves may burn.