What mad_gallica said. Any rose which suckers can be treated the same way as reported. My experience has been that those which sucker readily are more easily propagated through the suckers than by trying to root them.

I've had good luck digging up suckers when the plant is dormant and weather is cold. I pot them up in 4" pots, keep moist, and they become well rooted sometime in spring. Some people might sever the connecting root before digging up so that the sucker puts out more roots right under the plant before digging up. Usually the feeder roots are pretty small on a sucker. If so, you might cut back the top growth some.

So how long a length of sucker connecting root should be attached? Do I cut it long and coil it around in the soil in the pot or just a few inches long so it sticks straight down in the pot? That's also a great idea about leaving it in the ground for a bit and just severing the connection to the mother.

Gallicas are non-starters here ... but other roses will do it, too. My husband has made literally dozens of new plants of "Grandmother's Hat" by potting up suckers.

I've found that the ones to root quickest are those with at least some side roots to the underground bark covered sucker length. Under the right conditions, most of the ones without any side roots eventually succeed, but those with side roots do it more readily.