Do I need to wrap the stem of a Rose Tree for Winter? If so what would you recomend? I have six and they all have a well around them which I will completely fill with Hay/Straw for winter.
Arapahoe County Colorado trees and shrubs
Tree roses, commonly called Rose Standards, are created by grafting 1 to 4 desirable roses on top of a long rose cane with no foliage (usually about 2 - 3 feet tall).
The problem with tree roses is that they are generally not cold hardy in Colorado's climate. With extensive protection, most rarely make it through the winter if they are planted in ground. The stem is probably hardy, but the grafting is located at the top, and is not able to withstand the cold and wind, whereas, with regular roses the graft is at the bottom and can be surrounded with the collar (as you mentioned) and filled with soil and leaves, covered with evergreen boughs and other insulating materials.
There are a couple of things you might try, but there is no guarantee, and it may be a lot of work for six rose trees:
After the roses goes dormant, wrap the tall cane (you call it the stem) with tree wrap starting at the bottom and go as far up as you can. Find the grafts at the top and wrap those with tree wrap, burlap or pieces garden frost row covers. Be sure to not use any type of plastic material as plastic does not breath and is a conductor of cold. Place another burlap bag over the top of the rose tree and secure. It should look like a tootsie pop wrapper (see photo below). Keep the rose watered during warm, dry, snowless periods throughout the entire winter. Unwrap after the threat of freezing has passed in the spring, then prune, fertilize and water.
You may also consider doing an inverted version of the in-ground winterization by making a narrow upside down 'cone' out of chicken wire. Again, wrap the trunk and grafts with pieces of burlap or frost row covers, and then fill the cone with leaves, compost, etc., then wrap the entire cone in burlap. This will look like an upside down pyramid.
In Colorado, a lot of gardeners who grow Rose Standards do not plant them in ground, but rather, opt to plant them in large patio containers. Containers are portable and can be moved into a cool garage or shed for the winter where temperatures should stay a consistent 32-45 degrees. This will also require wrapping the tree and watering occasionally throughout the winter so the roots do not dry out, then bringing the containers back out in the spring after the danger of freeze temperatures have passed.