They sure can, with a little TLC. I myself only have "textbook" knowledge on flytrap care, I am new to growing carnivorous plants and still keeping to those without a dormancy requirement. For now at least. I think you will find this link very helpful.

http://www.thecarnivoregirl.com/winter-is-coming-a-guide-to-venus-flytrap-dormancy/

They do not die, so much as go dormant. They still need some care during this time (water, but much less, and light), and outwardly may appear dead, but below the surface slumber and await the return of warm weather.

I would not keep them outside in 6. I'm in 6 and It's too cold here. They can take brief freezes but that all.

Well that may work but you'd have to keep an eye on the inside temp. Mine live in the fridge until the end of Feb./Early March. Been doing that for over 9 years.

I do know folks in zone 6 (don't know if a or b), who have kept vfts outside year round in a mini bog with no prob. Believe they said they just mulch it with straw in late fall.

Coldframe should be workable though you may have to experiment a bit to tweak out any "bugs" in the system.

I have has a VFT growing outdoor in zone 7A with no problem. Last winter we got down to 0F and 20" of snow. Come May, it just puts up small green shoots and eventually gets full size. It's in part Sun and planted in a mixture of miss and soil. I keep it wet all summer.

I know, old thread. But, I wouldn’t give up hope. People for some reason seriously think these are tropical plants when they simply are not! In fact, the reason they die indoors is because of a lack of dormancy period. People baby this plant around. In this plant’s native range in coastal NC has experienced negative temps before. It’s definitely safe in zones 7-9 and maybe even zone 6. It’s not really a tropical plant that is frost sensitive, it needs frost.

“It’s not really a tropical plant that is frost sensitive, it needs frost.”

Not so. They just need a period of chilling, not actual freezing. They naturalize in Florida, and do quite well here in San Francisco where they never see even the 30’s F.

They would benefit from a frost though

They can take BRIEF freezes but no long ones or repeated freeze and thaws. Temps between say 33 F. and 45 are perfect. They DO NOT need to freeze.