The main canes cut off won't grow back. They can produce side canes from a leaf bud, or the plant can produce brand new canes from the bud union (if the rose is grafted) or from the base of the plant, (if it is a non-grafted own root plant).

As to how long the canes on your new plant will grow, it depends to an extent on the variety, but normally the first canes produced from a climbing rose will be far smaller, thinner, and shorter than the canes of a mature, established climbing rose.

The old adage about perennial plants, "the first year they sleep, the second, they creep, the third, they leap!" applies perfectly to roses. Depending on your climate, it may even be four, five or even seven years before a climbing rose really gets large and produces a spectacular show of flowers. Climbing roses are not instantly spectacular. They are a multi-year investment of patience and effort. Not to say that you will not get a few pretty flowers the very first year, but you'll need to be patient.

Thank you for your help. Is there a way to encourage new main cane growth from the bud union? Should I leave the old cane stubs or trim them back even more? Thanks again.

Your main canes when pruned or broken will not regrow from its end. The main cane comes up from the crown of the plant. From that cane it will grow whats called laterals. Laterals grow from whats called bud eyes on the sides, front or back of the main cane. If the pruned cane has bud eyes on left on it they will start to grow. When it is down low its like they are sort of replacing what was lost.

The old cane stubs, if they are healthy and alive, can produce some good new canes if there are some live leaf buds present on the cane. If they are diseased with blackened areas, or are completely dead (brown all the way through) it is better to remove them. If the cane is healthy, no need to shorten. Roses store carbohydrates in their canes, so when you remove cane, you are removing stored energy.

To encourage new main cane growth, regular water and fertilizer. A fluffy mulch around the plant but not in direct contact with the base helps to retain moisture and keep the soil cooler. Roses like their roots kept cool. Make sure the plant is not engulfed in weeds and make sure it's getting enough direct sun (6 hours+/day). In some soils a few tablespoons of Epsom salts (which provide magnesium) in springtime can be helpful, but be aware for Epsom salts MORE IS NOT better--you can poison the plant with too much. Measure the amount and DO NOT overdo Epsom salts.

I think you said it better, Patty W.!

That will never happen but thank you.

I have a 14 year old Golden Showers. It has a very large trunk and 2 or 3 main canes. Two years ago, when pruning it, I peeled off some of the loose bark from the base. This was very old wood. That spring the base spouted 4 new canes from that old wood. So you can try peeling the bark off, and of course fertilizing and watering will help. And direct sunlight on the base.

Alfalfa hay is really fantastically helpful for encouraging basal breaks (aka, new canes) Uber-high in nitrogen, and earth worms love it!

Do you recommend placing it on top of mulch, instead of mulch? Anything special to do to it?

Well, I guess digging it in a bit around the base,and then watering it in (if rain is scarce) would be the fastest and most efficient way to get it's nutrients to the plants roots...

lots of sun and water does it for me to encourage basal canes.

At a feed store you can purchase alfalfa horse pellets. Give your rose a cup of alfalfa. Alfalfa's a good organic supplement - use the extra pellets on your flower beds and lawn.