Salut Rémy,
Bienvenue sur le forum.
I live in Qc City so we can go to -40° but usually it's more -20° to -30° here too.
Outdoor growing success depends a lot on snow cover. If you get early snow, you're alright. If not, you're doom. A few years ago, we didn't had snow before february so a lot of casualties. Because of that, I prefer to bring my CPs inside the unheated garage.
Still, I keep to much plants to bring them all inside.
- D. rotundifolia make it outside.
- S. purpurea also.
- I also kept some pings outside for a few years but as they declined years after years, I started to bring them inside too. They don't like to get too wet so Spring was not easy on them.
- S. flava, yellow Pitcher Plant I bought from Urban bog stay outside and coma back year after year
- D. binata made it outside one year but I suspect new plants grow from the 1st season seeds on the 2nd year
- D. californica made it outside 1 year. My bog was shaded so I wasn't able to give it enough sun the year after and it died. If you try it, I would recommand to give it a lot of sun with good water running near the roots.
- I started roridula seeds under snow cover and they sprout in Spring.
- I will try a ceph one day
My main problem is that my growing space is shaded and that's no good for CPs.
At least here ... Summer is so short.
Good luck.