the same pretty much goes for any potted plant, heat is evenly distributed by soil, in a pot, wind, rain, you name it, can strip the heat out of a pot and turn it to an ice cube in a suprising short period of time... try an experiement if you live some place cold... fill a pot of up with soil, and keep it moist. When the first extended cold blast comes through, snow falls, and fun begins, the pot will freeze up, yet you will still be able to dig into soft soil in the ground, shows you the difference...