Carnivorous Plants/Inside in winter
I have just starting trying carnivorous plants and have a S. Purpurea and two others that I grow in a highly lighted lab at my school during the winter. This is the third winter for the S. Purpurea and it seems to be doing fine with a few dead leaves. Living in Louisville, Ky. where the winters are very unpredictable I was wondering what the advantage was to leaving them outdoors in the winter. It really makes me nervous to leave plants in pots even highly protected in the conditions we have experienced this year. Thanks.
Keith from Louisville
As you've already discovered, Sarracenia can tolerate a minimal dormancy, so many people can be successful having them in windowsills during the winter, and for just a plant or two, that works fine. It can also work for plants like Venus flytraps as long as the window is cool enough. It doesn't work for most North American sundews or European butterworts since they need a colder winter. (Hibernacula on these plants don't form properly, and they almost always rot out.) As people acquire larger collections, however, that's when this becomes impractical, and setting up some kind of cold frame for the plants is often the solution.
Let's deal with your core question, however, which is there an advantage to keeping them outdoors during the winter. The answer is it really depends. As I write this it is 21 degrees outside, and all of our North American Plants are under plastic covering, and have two inches of snow on them. Their pools create a cold frame, and sometimes we loose a plant or two, but in general, they do fine. Our coldest so far this winter was 8 degrees F. In our case, having several thousand plants, greenhouses would be impractical, and I can say I've lost plenty of Sarracenia that I was trying to "protect" by keeping them in a greenhouse. I've also talked to more customers that have lost plants to fungal attack or rot when kept indoors for the winter than customers that have lost plants to freezing when properly set up for the winter. Here's a great example of how they can be situated in a climate much colder than yours: http://www.carnivorousplants.org/howto/GrowingEnvirons/BogOntarioCanada.php
How you winterize your plants may depend on you situation, and what is most practical for you to do depending on your collection size and the spaces you have to keep plants. We go into detail about this in a chapter on our volume #1 DVD: http://www.growcarnivorousplants.com/Grow-Carnivorous-Plants-DVD-1-p/01111.htm
The bottom line is, however, that these are North American plants, and they do need a dormancy period. When it comes to climatic issues you have to look at carnivorous plants exactly the same way you would look at other perennial plants. When plants have the proper dormancy the usually grow better the following season, bloom properly, and are generally healthier. Do you have Lavender, Strawberries and Roses in the lab during the winter? These are plants with similar hardiness. Carnivorous plant growing is gardening and the same principles apply.