These are examples of roses I overwinter (zone 3) in the garage:
1. Grande Dame
2. Neil Diamond
3. Pink Peace
4. Memorial Day
6. Nicole Carol Miller
8. Night Owl
9. Buxom Beauty
10. Young Lycidas
12. Baronne Edmond de Rothschild
13. Peter Mayle
14. Betty White
15. Chandos Beauty (my favorite rose)
17. The McCartney Rose
19. Lucille Ball
20. Parfum de Grasse
21. Radox Bouquet
22. Lasting Love
23. St. Ethelburga
24. Carole Bouquet
26. Big Purple
30. Paradise Found
And many more. I never have a loss (well, except for one year...I had 4 losses...but I experimented (too lazy) with not covering them.
So what I do is this:
1. I start taking all the leaves off (at the cane) when the night temps are under freezing. I take a little off each rose as I have 55 or so to do this for (so that every rose starts to lose leaves).
2, When the temps get to -3C (26.6 F) or -4C (24.8F) I take all the leaves off (it's a marathon
). The coldest you should leave them out overnight (in the fall not the spring) is -6C/21F. If you have really cold sensitive roses then put blankets on them.
3. So then all the leaves are off...I water the roses really well. Then I water them again really well.
4. Then they go into the garage. I place them on leftover long pieces of hardwood. Then I leave them alone. I have roses that go right to the front of the garage.
5. When the temperatures get to -10C/14F at night, I put flannel sheets (from Value Village or someplace cheap) over the roses. When it gets to -20C/-4F I put more blankets on, and sleeping bags on the ones near the door.
6. Then around January or February I give them all a cup of water. Thereafter, every month they get another cup of water.
7. When the temps start to warm up (spring)...I take the blankets off.
8. They can go outside (if you have a few rose pots that you don't mind dragging in and out) when the temps are +5C/41F. If you're going to leave them out...then the night temperatures should be 5C/41F. For the occasional low night time dips...cover with flannel blankets or bring them inside.
Also, with blanketed roses, I am able to leave the garage door open while we shovel the snow, unless it's colder than -20C/-4F.
I hope that helps.
Caveat is that my pots are resin pots and are about 25 gallons. If you have much smaller pots or terra cotta pots...then this probably will need to be adjusted.
Another caveat is that I had a potted mixture made by a big company...they no longer make this potted mixture...so I'm using more of a 5:1:1 mixture with faster draining soil. So I'm going to be closely monitoring those pots to see if this needs to be amended. I may need to bump up my first water much earlier.
And yet another caveat is that my garage is insulated but not heated.