I think your garage is too cold, although you can try covering it with blankets when it gets below freezing. rosecanadian does that going from sheets to comforters as the cold progresses. I'll try to find her procedure as she is in Z3 British Columbia and keeps almost all her roses in pots in the garage! Do you have any sort of protected cool room perhaps that doesn't get too cold that you could bring it into during the frigid spells? I keep mine in an unheated sunroom and they do fine, but they will break dormancy early so I have to watch out for aphids sometimes. You will have to water it about once a month and make sure it is well hydrated before putting it to bed. The problem with indoors is humidity, pests, light and too high/dry temps. I keep my rooted cuttings and many tropicals in a room that's in the 50s in general going lower at night with a florescent light over them from late afternoon til midnight. This is an east facing sunroom also. They do well here as well as the temp variation isn't as great as that of the unheated southern-facing room. I had trouble keeping them in my other rooms even when cool for some reason, probably light.

Thankyou for responding. I believe I will try the garage and bring them in on extremely cold days and nights. I have wintered 3 potted roses in the garage for the last 6 years and they do fine. The little ones are so tiny I am concerned for them. I will be watering them occasionally and hope for the best.

I forgot to ask you if that was 0 degrees Celsius or Fahrenheit! I'm guessing Fahrenheit. Your plan sounds good by the way. Rose Canadiens garage is unheated also but it's insulated and I believe it's also attached to her house which may make a difference. When it gets really cold she puts blankets on them as I mentioned above. Please report back in the spring and let us know . Good luck!