These are the rose and blackberry cuttings that I stuck into the ground in December. Mostly it's been a chilly winter with lots of rain, as usual, some snow, and a few good freezes into the teens. Other than a leaf mulch, I did not protect them.
Here's how they look now.
Climbing red rose.
Old heirloom rose, unknown variety. Fragrant old rose scent, highly double pink flowers, very thorny green stems.
And a thornless blackberry.
I can't promise that all of these will grow, but they usually do. It's a good sign that the buds are plump and green or greenish-red. And the stems look good.
I think this method might work especially will in Pacific Northwest mild wet winters.
Long before there was rooting hormone, greenhouse sprinkler misting systems, etc, gardeners propagated lots of plants this way, including roses. My great aunts, Rose and Alice propagated stem cuttings in southwestern Illinois, with mason jars to keep them from drying out. They were probably taught by their mother in the early 1900s.