On 2016-02-23 21:40:43 +0000, David E. Ross said:

I want to try to root cuttings of a rose from someone else's garden
(with permission), a rose that is no longer available commercially.

The question is: what type of cutting is most likely to be successful --
succulent new growth, somewhat woody but green almost mature growth, or
truly mature growth?

I haven't rooted any rose cuttings, but I'd imagine nearly woody slips
would be best. You can root them in non-nutritive media such as
perlite, peat moss/sand, vermiculite, etc. using rooting hormone. Take
a cutting with a good growing tip and a couple of nodes, strip the
leaves off the bottom node or two, rough up the phloem a tad on the
bottom half inch or so of the cutting, dip in a bit of rooting hormone
and place the cuttings into the moist medium so as to cover the bottom
bare nodes, mist the medium aroung the slip to get good contact, and
cut about half of the tips off the leaves to reduce transpiration.
Place a plastic baggie over the container and place in bright
artificial light or indirect sunlight.

Better yet, if you plan on doing a lot of cutting propagation in the
future, consider building a bubble cloner. I made one similar to the
following and have been amazed at how quickly I can propagate chili
peppers with almost no losses.

https://forum.grasscity.com/do-yours...le-cloner.html