Answer: It doesn't sound as though the growing conditions are quite right for your moth orchid. Here are a few pointers:
Flowers of the Phalaenopsis Orchid have superb longevity. You can often urge a second flowering from each spike with a timely pruning.
When the last flower of the spike fades, you should examine the spike, looking for small fleshy bumps or nodes. From the base of the spike count out 3 nodes (count only the green fleshy nodes - ignore any that are dried out). Cut the spike one inch above the third node.
If your plant is healthy and the season is not too late, this process will wake up one or two of the nodes and in a few short weeks it may produce a new spray of fresh blooms. By trying this you could enjoy flowers for nearly 6 months of the year on the same plant.
Phalaenopsis orchids will enjoy a spot near or in a bright window. You'll want to avoid direct mid-day sun but early morning or late afternoon sun is great. An east or west facing window is ideal. In darker or cloudy environments a shaded southern window might be best.
You can supplement normal light with fluorescent lights placed approximately 1 foot above your orchid. Time your lights to simulate normal day length. If you have a home greenhouse you should consider using a heavy shade cloth (especially during the summer) to limit light levels to 1,000 - 1,500 foot candles.
The ideal temperatures for the Phals range between 55 and 85 F. For ideal growing try to maintain 60 at night and between 75 and 80 during the day.
Cool night time temperatures in the fall encourage flower spike initiation. However, once the flower spike is developed, wide swings in temperature can cause unopened bud to drop off. Temperatures in excess of 90 can slow growth.
Phalaenopsis also benefit from moderate humidity levels. Ideal levels range between 50 and 75% relative humidity. In a heated home you will want to set your plants on a shallow tray filled with gravel and water. This should help to keep the humidity near your orchid at acceptable levels. Make sure that the plants roots are NOT sitting in water.
Moth orchids do not like to be dry to the point of wilting. They should be watered thoroughly and then not again until the media is nearly, but not completely, dry.
How often you water will depend on the type of media your orchid is growing in and its growing environment. Once every week to 10 days is a good starting point.
In winter, with the heat on in your home, lower humidity will mean you'll water more frequently. Don't let your plants dry to the point of wilting - it will really set them back.
Remember to not get any water on the flowers as this will shorten their longevity.
For convenience, a slow release fertilizer with equal proportions of N-P-K (14-14-14) used as directed, can work very well. If you prefer to use a liquid plant food, again with equal parts of N-P-K, apply it at recommended rate every second time you water.
During blooming season you might consider a blooming plant formula with elevated phosphorus levels (i.e. 10-30-20). During winter months you can reduce liquid fertilizer applications to once a month.
I would recommend staying away from fertilizing altogether while the plant is flowering.
Hope this information will help you help your orchid grow strong and healthy and bloom several times a year.
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