i usually wire a piece of plastic with some slits in it to let in some moisture, but keeps inquisitive rodents out, over the top of the pot for protection. i wouldn't mulch it heavily because you don't want it too protected from temperature swings - you want it to freeze and thaw a few times before spring. i suppose just planting the seeds directly in the ground could work too, but i find it easier to transplant from the pot. some other seeds need more protection from
mice than this, but kousa seeds don't seem to smell too enticing.