Well, last year the greenhouse survived until January with crappy Home-Depot cover-your-boat/motorcycle-plastic and this year it only made it until mid November with proper greenhouse plastic. We had a few days in a row that never made it above freezing and that did me in. In my defense, this winter is wayyy more severe than last winter, which in comparison didn't even really seem like a winter. We've already gotten probably a total of two feet in snow (one foot from just a single storm last week) this winter, which I love. The outlet tubes freeze up since they aren't all that thick and then the tubes will overflow and eventually the reservoir runs dry and my pump could break, so I decided to end the season. Once the tubes the plants are in freeze solid they can crack some of the endcap seals and it just isn't worth it.