Malaysian, clay, ceramic, and concrete pottery can deteriorate in the winter without proper care.  The moisture in the ground can be absorbed into the pot and when the temperature drops, the moisture in the pot freezes.  This can cause the pot to crack or bust.  The pot can be left outdoors if you put them under shelter, off the ground and remove the soil.  If you have a garage, this is the best place to store your pots.  If the temperature in your garage doesn't get below freezing, you

can also leave the soil in the pot.  If you must leave your pot outdoors, the best thing to do is remove the soil, turn your pot upside down on a wood plank or something that will keep it off the ground.  Next, cover your pot to help keep out the moisture. Again, it's not the moisture that hurts the pot, but the freezing of the moisture.