When we had a cold winter in the country, I bought several bales of hay. Then, I fluffed the hay around my small pots. When there was a threat of a freeze, I deeply watered all my pots. I had a large pot ghetto. Hope this helps.

Exactly how warm does your garage stay in the winter? I don't have a furnace in my attached garage, but it is very well insulated and rarely went below 40F despite temps outside going as low as -5 to -10.

Is there a corner of your garage farthest away from the furnace/hot water heater that is not as warm? As long as they are kept in the dark, even if you have to makeshift some curtains or something to keep the light out.

I haven't overwintered roses, but I've had very good luck overwintering a lot of perinnials in pots. I usually set them up in an area protected from the winter wind, but where they would receve natural moisture (rain & snow). Then I surround them in straw, and after they have hit true dormancy for a couple of weeks, cover them up with a thick blanket of straw.

In the spring you have to make sure to get the top layer of straw off as soon as it thaws (usually you can peel off a layer every couple of days or maybe each weekend). There are several perinnials that are forgiving if you don't remember that step until late spring (I haven't lost any yet), but I don't know about roses.

This year I will find out if this method works for me with roses.

veilchen - I am not sure how cold the garage gets. I think I'll put a max/min thermometer out there this winter and see for sure. If I wanted to get the roses colder, I could put them in the corner away from the furnace and next to the garage door, which does let some cold in. But, I thought I wanted to keep them colder than I think it gets out there so that they wouldn't grow. Is getting them into the dark what will prevent that? Maybe I don't understand the philosophy of wintering over. And if they're in the garage, I'll have to give them a little water over the winter, won't I?
Maybe the thing to do is put half in the garage, in the dark, where I actually have wintered over fuscias successfully, and half outside with leaf protection because I don't have access to the straw bogie and autumnshowers use.
Thanks to everyone for the input. I am the most avid gardener I know, so I usually go it alone on questions like this, but it seems a shame to have to reinvent the wheel all the time if others have solved the same problems before me.

Ideally, what you are after is a dark space that stays between about 20 and 40F all winter. For all practical purposes, unless you have an old-fashioned root cellar, this ideal is only reached by someplace with fairly serious climate control.

If it gets too cold, the relatively unprotected roots will freeze and the rose will die. This is fairly serious. In a real zone 5, where -15 isn't some theoretical temperature, but something known to exist on real thermometers, this will probably mean a heat source. The usual thing is to tap thermal leakage from the house, either in an attached garage, or in a pile next to the house foundation. My personal feeling is that foundation heat is adequate in zone 6, but becomes problematic in zone 5. Of course this depends on variables like the foundation construction.

If it gets too warm for too long, the rose breaks dormancy and starts growing. The problem with this, is that the short winter days, and relative lack of light inside means that the rose is not going to get sufficient light to thrive. Depending on how large and strong the rose is in the fall, it may or may not have the energy resources to break dormancy, produce useless foliage and then refoliate when the light levels increase. Darkness can fool the rose into staying dormant a bit longer, as can some dryness, depending on the ancestry of the rose.

Since fall is our rainy season, the pots tend to go into the garage quite wet. They rarely need any water before the middle of February. However, that is when they usually break dormancy for me, and when they start needing water and light. I can usually ignore the light issue for a couple of weeks, so they don't have to start going outside until early March. Then they go in and out depending on the weather forecast. Having spent the winter in zone 8, they are completely out of sync with what is happening in the normal garden.

I have heard other people use leaves, compost, or dirt to cover their young plants.

If they are only potted bands (I am assuming no more than 12 inches high) and your garage stays above freezing by at least 15 to 20 degrees why not continue to grow them to more robust plants for spring ... of course this means care and attention for stopping mites, doing watering etc. and not an easy task.

I have never succeeded with the garage approach yet but do grow them in the grow room and the hassles are mites and vigorous growth requiring pruning by February.

riku - thanks, but I don't really have a suitable place to grow them on through the winter and I've heard about all the problems with doing that.

mad gallica - thank you, the philosophy is what I needed, and explains why so many died in the shed last year. It got just too cold for them in there. I'm not crazy about wheeling them in and out of the garage in March, April, etc. but I guess I could put them in a wheelbarrow all together, and give it a try. I'm still leaning toward trying half one way and half the other and seeing what happens

I get my potted roses through our zone 4 winters by either of two methods: burying them in a 1.5 foot-deep trench along the southeast house wall; or covering them in plastic and placing them in my five-foot deep basement egress. The latter is pretty easy to do -- I've taken Tea roses through winter this way.

Bales of hay and leaf bags never worked for me. The death-by-unheated-garage was a cruel experiment for my potted roses. The garage would stay in the low twenties when the door was closed but the temperature would quickly drop well below that when I open the outside door in Dec-Jan-Feb.

The best insulation for potted roses is in the ground so I was told. I have about 7 roses that I am SPing soon and the holes that they come out of are going to be filled with my potted plants. I am just dropping the pot in the hole and covering it a little around the base with some cedar mulch, I will take the pots out in the spring around the end of April. Although my zone 7 doesn't get that cold in the winter I still want them protected.