Here is the new sheet I am going to this weekend's show armed with. It will take forever to get it up on the web so I just cut and pasted it here.
Pat
How Do I Water My Orchid Properly if it's Planted in Moss?
We plant all our phalaenopsis and some of our other types of orchids in long-fiber sphagnum moss. This is not your usual craft store sphagnum moss, which is a short, stubby fibered thing used for decoration. This is a sterilized, long-fibered moss from New Zealand, Chile, or other locations around the world. Because it is long-fibered versus short, it will stay light and airy in the pot and not pack down into a wet mess. We really do favor this potting medium because we have found it to be clean, less hospitable as a home for bugs than bark, and easy to detect when the plant is ready to be watered.
So how do you know when to water your plant? Well, you give it the "pinch test." Pinch the moss at the top of the pot, no deeper than the first knuckle on your index finger. If, when you pinch the medium, you can feel moisture, do not water. If the mix is dry when you pinch it, then it's ready to be thoroughly watered with lukewarm or room temperature water. Take the plant to the sink and water the pot until the water is gushing out of the bottom drainage holes. I said pot, and I meant it. Don't let water splash into the leaf crevices and sit there. That would encourage crown rot, which is often fatal. You water this way to simulate a quick, tropical thunderstorm, which is what the plant would have gotten in its natural habitat. Let the plant drain thoroughly and then put it back wherever it was growing happily. When you put the plant back, do not turn the plant like you would some houseplants. Orchids like to maintain their exact same orientation towards the light. Turning them forces them to adjust and will discourage and confuse them.
I must address some watering silliness that has popped up from big box store sellers. The watering instructions on some of the orchids they are selling tell you to put a certain number of ice cubes on the plant every week. I can only assume that they believe your expectations for your orchid are the same as if it were cut flowers. Watering with an ice cube will prevent you from killing the plant by overwatering while it is in bloom. Then they expect you to toss it in the trash like a spent bouquet and buy another.
Tropical plants like orchids have never met an ice cube before. An ice cube touching a leaf or root will kill that tissue. Over the long term, ice cubes will not provide enough water to sustain the plant. Food can not be delivered through ice cubes. If you plan to keep your orchid for any period of time, do not put ice on it. Enough said.
All of these instructions are appropriate for our plants potted in our long-fiber moss mix. If your plant is in bark, please ask the grower for his instructions on proper watering. Enjoy your plant.