Whether you grow your North American pitcher plants, sundews and venus flytraps in a dish garden or in your yard, winter care is easy. They are cold-hardy to 20F in a pot and 0F in the ground.
Dish gardens need protection if it gets below 20 degrees Fahrenheit. In Zone 7 and warmer dig a hole and put the planter in the ground. Mulch with pine needles if it gets below 0 degrees Fahrenheit. Alternately, if you live in a colder climate, over-winter your dish garden indoors. Just make sure your plants aren't growing leaves in the winter; they need a rest!
If your plants are in the ground and the weather forecast is calling for sub zero temperatures (in the negatives), then mulch with six inches of pine needles. A layer of pine needles is a good idea anyway; it holds in the moisture during the summer!