I have a friend who just covers her new ones each year with clear glass jars and it works well for her. Not an expert but I know it works for her and I am going to try it this year with the two new ones that I planted directly in my garden. If they are too tall you could trim them back enough to fit into the jar not touching the sides or top of the jar.
Angel

Roses are tougher than begonias, they can take a little frost. However, you will probably want to protect your new cuttings from a hard freeze - defined here as 5 or more hours at 28For lower.

As a temporary measure, you can just cover your cuttings with an old sheet or blanket. after your roses go dormant and before single digit temperatures, you will want to have some winter cover in place. Bottomless pop or milk bottles make nice individual cold frames that can be covered with leaves or straw in the coldest months.

Regards,

Charles

I'd try the jars myself. When they lose their leaves if they do, I'd cover them with jars and leaves, then remove them in the spring. I have a few like that now covered with jars, but I started them with jars because I ran out of pop bottles. As long as the one is still green, I don't want to deprive it of light, don't think the others look like they are going to make it, leaves cooked off but stems still green on some. I'm not peeking. If it warms up too much, since they haven't been under jars, they could cook, so I'd watch that carefully, or do like one lady's method, rinse the jars with a little muddy water to diffuse bright sunlight. Congratulations on getting some rooted that way. I tried that with some extra cuttings, and they were the first to flop. Maybe like the other poster said they are hardy and will survive in situ as is.

From what I've read on various sites; cover them with the jars or mound them but do not cut them back. The muddy water method sounds so effective. I've got to remember it!

I wouldn't worry too much about overnight lows in the mid 20s. Even a potted cold tender tea baby can take that in its stride, assuming it's already adapted to life out of doors and is protected from the wind. Our lowest winter temps are typically in the mid to high teens, and I never bother to bring rooted cuttings inside anymore. I just cluster their pots in a sunny, wind protected area at the beginning of the cold season and they do just fine. They'd be even safer in the ground.

Of course I can't tell you what to do later in the winter when it gets cold enough, long enough, to freeze the ground. That almost never happens here.

Instead of just plastic pop bottles I would suggest using gallon size clear plastic bottles such as are used for grape juice or apple juice. Simply cut out the bottom and save the cap for temperature control. This gives you consider more room than a one or two litre pop bottle
Good luck!!

charliebear makes good sense. I'll have to remember the advice!

If she's too far north, she's probably under 6in of snow. Hopefully she did something to protect them.

I've had success overwintering roses two ways- If they're in pots, dig a ditch or trench, put the pots in and cover loosely with leaves, soil, or compost. If they're in the ground, mound fallen leaves over the plants. Completely cover them and leave them. Mine are against a fence, so they're not disturbed by wind. A cover of snow is good, it acts as insulation. Good luck with yours.

Cold and wet for extended periods is very conducive to various kinds of rot in newly rooted roses. Phyton 27 used regularly helps, but I've found in Oregon it is necessary to protect them from rain. We carefully hand water to keep them just moist.

Rain is a problem for me as well, as are the yo-yo temperature swings we get during the winter. We do get occasional lows in the teens, or even lower, but I've never lost a rooted cutting to freezing weather alone. In my climate the real problems are caused by the dormancy breaking mid-winter highs in 70s and the rain that tends to coincide with the wild temperature swings. So every winter I worry less about protecting the babies from the cold and more about protecting them from rot by becoming ever more obsessive about maintaining good drainage and good air circulation around the tops of the plants. That means no trenching and no covering.