Sorry to hear this news...
How cold did your Temps reach at night after you pruned and after removing from garage?

I don't remember - but probably between -10C (14F) to -5C (23F). Plus I had a thin blanket over them. But they were on the driveway - so there was cold cement under them.

Carol

That may of been just alittle to cold for container plants.
Maybe try bringing them out alittle later next year.
Overwintering container roses in zone 3 is probably a real challenge.

Yeah it is. But I'm determined, and my husband is monetarily patient. :)

I will bring them out a little later next year. I brought them out because of all the new growth. Do you have an idea about what is a good overnight low to bring them out? I write down everything I learn about overwintering roses in my book. So evenually I'm hoping to be a pro at this. - hopefully.

In the meantime I have about 20 roses that made it and I have 21 new roses coming!!

I really appreciate any help you can give me.

Thanks,
Carol

Your zone is probably a real challenge, so do not feel bad if some die.
Do you have any types of Rose Societies up there in Canada?
That would be the ideal people to ask your questions.

Too bad you couldn't bring them out on warmer days, then put them back in on expected colder nights.

To minimize work, get a large garden wagon and place your potted roses in it to bring them in and out. On warmer days above freezing and nights when it's above 25F they can be left out but should be moved back inside if it's forecast to drop below that temperature.
Your garage should not be heated and the roses stored away from any light source. Don't take inside in the fall until they've gone through a couple of freezes and have begun to go dormant.

My husband took two old doors and put caster wheels on all 4 corners of each door. He then attached a rope handle. I load my potted plants on the flat doors and just pull them in and out of the garage. The doors have plastic tarps on them to keep the water from rotting the wood. Works like a charm. Speaking of water, are you watering your roses a bit every 4-5 weeks during the winter, Canadian Rose? I've found the one thing that will kill my overwintering roses is if I don't remember to water them regularly. Doesn't take much water, but really important. We also put sheets of styrofoam under the roses and against the wall behind them during the winter for extra protection from the cold.

Yes, Karl - I've already done that wrong in the past LOL. The first year I brought them in when the green leaves were still on the bushes. Did not go well.
Jim - I've tried e-mailing the rose society here - they don't respond. And Karen's idea might work - though I'm doubtful since I have so many pots and they're so heavy. But, I'll ask my husband - the idea might be just the ticket.

Karl - I thought that the temp in the garage is not supposed to go below -7C (19.4F). So that's what my garage ceiling heater does. It maintains the temp. Am I wrong?
Karl - Too many roses in too large of pots to go in and out. Better probably to take them out later and cover them with blankets.

Karl - If I do leave them in the garage longer, should I cut off all new growth?

Karen - Your ideas are good - but the pots are just too heavy to lift onto something. Although I will tell your idea to my husband. He was talking about buying a winch of some kind to lift them. So maybe that would work.

Karen - Do you think I'm watering them too much? I watered every month by dumping a huge shovelful of snow on top of each rose.

You've all been so helpful!!! Please keep the answers coming.

Carol

I overwinter my potted roses in an unheated greenhouse where the inside temp drops close to the outside after the sun goes down. The pots freze so hard I can drive nails with them, but they bud out as soon as they thaw, the sun rises higher in the sky, and the days get longer By early March I have to prune them.
If the temperature is too warm inside your garage, you'll get leaf out too early. Don't turn the heat on next winter or at least set it lower. Are there any sources of outside light? Shouldn't be! Lots of heat in sunlight coming through a garage window.
If the growth is green and healthy, leave. If white and long due to reaching for the sun, remove. It'll shrivel up and die anyway when exposed to the sun.

Thanks Karl. I'm thinking though that my outside temperature and your outside temperature are quite different. If you tell me what your outside temps are approximately - then I can adjust my heater to that temperature.

No, there are no windows in the garage.

Thanks,
Carol

The coldest winter night time temps in my area the past few years have not dropped below minus 10F. I'm sure your coldest nighttime temp is considerably colder.

I don't think it was the pruning that killed them. Some people prune in the fall before winter and their roses do fine. I think you may have jumped the gun and brought them out of winter protection too soon. Once they wake up and start growing it's the freeze and thaw that will kill them. You want to try and keep them dormant until might temps are consistently above freezing. New growth can take temps to about 28 degrees before there is permanent damage. Anything lower and they're pretty much toast. Then the rose has to start regrowing new shoots again and there in lies the problem. The dormant rose only has so much stored energy from the previous season with which to start growth before it needs those new leaves to provide more energy. If it uses up all it's energy starting over and over eventually it just can't do it again and dies.

Karl - that converts to about - 12C. Yes, we get considerably colder than that. So I think I need to use the overhead heater.

Seil - It hasn't gotten that cold since they've been out. But it's been pretty cool (about 39F) for a very long time. It's just been rain and coolness for ever. But I think you're right - I got them out too early. I will learn and not do that again.

Thanks!
Carol