Keep the drainage hole open and the pots slightly raised above the ground. Your plants will need less water in winter, but they will need some. Keep a watchful eye, and water if there is a winter drought. If you live in an area that freezes part of the winter, most containers will have to be protected from the elements. Terra-cotta planters run a high risk of cracking because they are porous, meaning they have air spaces in the sand that is fired to make them.
Water seeps through the tiny air bubbles, and if it freezes, the water expands and cracks the pot.
Plants need to be watered and continue to drain throughout the winter, so do not wrap the top or bottom of the container with the plastic. To finish the job, wrap the bubble wrap with burlap. The burlap can cover the bottom because the water will pass right through it. Tie the top of the material with heavy twine, leaving 8 inches flapping in the wind. Untie the twine when it s time to water.