It will eventually grab on to most woods. I use thread to tie it to things. The key though is too start with a thin layer as weaver said for a good grab and healthier moss. If you cant see through the moss layer to the piece you are using then its too thick to start. Once it gets going it will need trimmings to keep it healthy and the layer thin or the bottom moss will die off and float away again. My favorite moss seeding stone is lava rock. It is very coarse and porous allowing the moss to stay healthy even when its a bit thicker. Also small pieces are easy to remove from the tank to trim and rinse mulm from because they do trap debris.
One more thing... a month is not very long especially if conditions arent perfect.