Millet, no. The plastic meets the ground. When it's warm outside I place blocks of wood or pots or whatever under the edges of plastic on the walls and open door to help vent tree. I've heard of some folks leaving an open gap at bottom of their enclosures and then packing straw or mulch at base to insulate more "on cold nights"; however, it gets extremely cold here and stays cold here for days, nights, weeks. A few years ago it hardly got above freezing for entire month of January. I have too many citrus outside to run around every other day moving piles of straw/mulch. I can open a door in morning before driving to work, and roll it down and tape it shut with strips of duct tape at night. Often it's already below freezing here before I get home from work around 5:30 PM in winter.