This is an answer to a question I received via Tree-Mail.
Spanish mass is indeed gray but when it is long-dead, it will turn black and be as fine as a thread. When it gets to this stage it holds no water. Since yours is still gray, it will hold some water, but not a lot of it. Now, if it is still viable, the moss will actually give off moisture, and my tropical plants seem to like have living Spanish moss adjacent to them. My orchids are no different. In fact, I have a large vanda who's roots grew into the moss that was hanging over the basket. For some reason all its roots have done this. One side of the basket is loaded with huge, stubby roots entwined with the moss and the other side has not a root. The basket is filled with coarse Douglas fir, medium horticultural charcoal, and chopped coconut fiber, medium chunks. I have not repotted this vanda in at least 5 years and perhaps 7-8 years. I know most of the Douglas fir has broken down but the vanda likes the way it is and I am not going to change its growing medium.
If your moss was bagged up, it is probably non-viable. You can pretty easily tell though. Dead moss will feel very dry to the touch whereas live moss will be soft, pliable, and slightly moist to the touch.
