I'll clean up around the place (leaves,twigs,bark,etc) gather everything up and put it in the larger breeding pens. I don't clean it out I just throw it over the old stuff, but i will clean them out once everyone is done molting and put some fresh stuff in there. I'll throw grass clippings in too lolI have been using mulch for the past year and it's worked good so far for me I will clean it all out spring and replace it with new