Question
SNW, I know highland nepenthes require a low night temp. of 40-50F so can you put them in a fridge. Also you say American plants require a cold period so to avoid fluctuating temps. and frost damage can you put them in the freezer at a steady temp at the sign of first freeze in winter.

Answer
Hi Nelson,

NO! Don't put your Nepenthes in the refrigerator.  If you do that, you will definitely shock your plants.  While many highland Nepenthes can tolerate temperatures down to 45癋, they experience these cooler temperatures gradually as the sun sets.  

Also keep in mind that not all highland Nepenthes require that type of temperature.  Only the ultra highland plants require it, but these plants are best reserved for the experienced grower.  Most of the highland plants best suited for first-time growers, such as yourself, can easily be grown in slightly warmer conditions.  Some of the easy-to-grow highland species include:
Nepenthes sanguinea
Nepenthes ventricosa
Nepenthes truncata
Nepenthes maxima
Nepenthes ramispina

With your Sarracenia, there is a technique of storing them in the refrigerator for the winter.  However, this is not an appropriate time to be thinking about winter dormancy.  Instead, focus on growing your plants the proper growing environment - outdoors in full sun and in a dish of distilled water.  This will keep you plant healthy enough to withstand winter dormancy.  If your plant isn't healthy at the onset of winter, then no matter what method you use to keep your plant during winter dormancy will be useless.  So focus on the appropriate care for the season.  In fall when it comes time to prepare your plants for winter dormancy, write back for more instructions.

http://www.cobraplant.com/caresheets

Good growing!
Jacob Farin