Most of my first year roses that I didn't put in the ground last year have made it through the winter. The past few winters I have been putting my pot ghetto in my shed. I keep them watered so they don't dry out and then come springtime out they come. I have found that I can keep zone 6 and 7 roses in there also and 9 times out of ten they make it through ( I am zone 5). I have found very little die back this way either so it gives them a good start. I have no room for a greenhouse or else I would have one in my yard. Most of my roses end up in my dad's yard about an hour away where there is ample room for the large shrub and species roses to grow.