Last year, our lowest temperature was 25ºF. Even though I covered my 2 Jamie Brugs with burlap, bubblewrap and then a fiberglass pot, they both died and didn't return. My Audrey Hepburn was bigger and a bit hardier and survived, but she didn't start blooming until August. Because our temperatures can fluxuate so much, I didn't feel comfortable leaving the bubble wrap on all the time. So I'd run out to wrap my 3 Brugs just before every freeze. I have more than 3 Brugs, but all the others are in pots. I was curious about how they would do in the ground using some of the techniques others mentioned.
In November, my DH made a PVC frame that we covered with thick plastic. I covered Audrey Hepburn with frost cloth rated to 24ºF then covered her with the frame and tied it down. She weathered the first 3 freezes really well even though the first freeze got down to 23ºF. A bit damaged, she even continued to bloom inside the mini-greenhouse. The first strong wind we had tore the plastic off. I ended up having to improvise. This is what she looks like right now — a great big cocoon. Under that cocoon, she is wrapped in 2 sets of C-7 Christmas lights, has 4 - 45 gallon garbage cans full of water surrounding her and one layer of frost cloth. Temperatures under the cover have stayed nice and cozy even the outside temperature got down to 13ºF one night. I'm hoping she'll take off as soon as I remove the cocoon.
