Soak sphagnum moss in water to hydrate it, then grab a handful and squeeze out the excess water. If using something like a 1×2 or scrap wood for a larger plant, I found it really helpful to lay the moss on the wood and staple over the moss into the wood to adhere it.
Also to know is, can I hot glue moss?
Secure Moss to Tray
When you get to a layout you like, use a hot-glue gun to secure moss in place. Because it’s a somewhat breakable material, I found it helped to unfold it off to the side of my tray, so that any dust or bits and pieces fell away. This helped considerably when it came to gluing the moss to the tray.