Good question today from my Facebook page:
How often are you supposed to water an orchid plant? My officemate got one a few months ago and it seems to be in sad shape. All the blossoms fell off, a bunch of leaves left, and the ones that are still there are turned downward and holding on for dear life. I've been putting it in the sun for a few hours each day. Any advice much appreciated! -- Michele Masterson (see photo)
What you have there is a phalaenopsis. These are tropical plants, which means they do best under warm, humid conditions. They like daytime temps to be about 70 to 85, and nights about 65. I don't know about yours, but my office is like a meat locker, which is very inhospitable to humans, let alone tropical plants.
It's best to keep phalaenopsis by a window. Also, they should be watered in the sink until water runs out the bottom, and then not watered again until dry. Just don't let them remain dry for long. Most growers use a "humiditray," which you can buy at many larger nurseries. You could also fill a baking pan or rimmed tray with small stones and an inch or so of water and place the potted orchid on top of the stones. You should fertilize it twice a month with a balanced fertilizer diluted to half-strength.
This type of orchid blooms once (or if you're lucky, sometimes twice) a year. The flowers stick around for 2 or 3 months. It's normal for some leaves to turn yellow and fall off, but not most of the leaves, just some. What you describe sounds like trouble. I'm guessing too much water damaged the roots, which in turn became unable to transport water to the leaves.
This would be a good time to repot it. Wash all the soil off the roots and cut away any brown or sickly looking roots (they should be white). Wash out the pot and replant with new media. If the roots are very big and seem crowded, go up only one size on the pot.