Tina, you're correct..Irish moss is not moss.

Here's a site that will get you started on learning the culture & growth requirements of moss.

Have fun...my moss garden is one of my favorite places.

Here is a link that might be useful: Moss Acres

Also if you want moss on rocks I think that you would have to collect some already if you are thinking of moss that grow on rocks! otherwise you need a kind of carpet moss that will grow over and between the rocks. For growing you need a mister spray head on your hose or use a pressure sprayer set to a mist spray. Being in Montana you have some major ups and downs in temps and you may want to check local areas and take images of what moss populations you may find there. Got any growing on the north side???
If you are near Glacier National Park they have a native plant nursery and do have mosses. I cannot find out if they sell mosses but you could find out if it is nearby.

Thanks for replying. I am in Billings and they don't sell any moss anywhere. I have a park a couple miles away that might have a bit I could scrape, I'm going to check today. If not, I might just buy some rockcap on Ebay to get it started. I think I will just plant the Irish moss I bought between the rocks. It's really pretty I think, and will assist the soil from washing down (the rocks are built up around the falls). Thanks again!

Tina

Neither "Scottish moss" nor "Irish moss" are mosses, so growing instructions suitable for mosses are not advisable for them. They are both varieties of the genus Sagina, which is a member of the Pink family. Saginae are native to cool windy moist climates, and the eastern US seaboard is generally a terrible environment for them. They thrive along the western seaboard of the British isles and on the US coast in Oregon. If you live in a hot-summer area, you should avoid them, and even in more moderate climates they will prefer shade and moisture. Think grottoes or shaded pools.

Here is a link that might be useful: Sagina varieties