It is only a semi-climber and shouldn't be too vigorous for an arbor.

John Cabot wants to get wide. It's slow to repeat so if you expect flowers all summer, you'll be disappointed. Mine grew at the base of a flagpole and was 6-8 feet wide and 7 feet tall before it was removed due to RRD.There are better climbers that will stay more within the bounds you have and will repeat better.
Do some more research.
While it was extremely hardy in my zone 5a, it would be the rose that ate your arbor in your slightly warmer zone.
John Cabot makes a great free standing bush but should be given plenty of room.
Here's my Sweet Autumn Clematis last fall.
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and John Cabot a year ago spring before it was clamed by RRD. That flagpole is 25 feet tall and the bush is over 7 feet tall.
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Hmmm-- John Cabot only gets about 5 to 6 feet tall here, even with a 12 month growing season and no die back. I wouldn't think it would be big enough to make a climber out of it. Also, the canes are stiff and straight up -- not something you could bend around a support laterally.

Kathy (in California)

My John Cabot is at least 7 feet tall and would be taller if I didn't keep trimming it to make it fit on my trellis. It is perfectly hardy and only has a bit of tip damage after a bad winter. I think it would be difficult to keep it to 2 feet wide as it is difficult to keep it to the 4 feet wide that my trellis allows. John Cabot keeps trying to expand onto the trellises on either side of it. It looks beautiful in the spring but doesn't bloom much after that.

Thank you all for your suggestions & advice.

daisy735 - how many John Cabot bushes do you have planted at your arch? To get him to bloom so prolifically do you take his canes back and forth, or do you just let him ramble? My arch is as wide as yours where he would grow up so it might work. As mentioned, his canes are to be very stiff and thorny. William Baffin was also suggested by someone, but I do not know anyone growing this rose.

Thank you. Jane

William Baffin has similar chacteristics as John Cabot but is not as well behaved. It can get quite a bit larger.
Go with John Cabot.
Here's a two year old William Baffin in spring. It was a constant fight to keep it contained. It does not repeat well at all. Just a few sporatic blooms after the spring flush.
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Janepa-I planted one climber on each side of the trellis. We pass thru this arch constantly to the garden and it faces the street so he requires frequent trimbacks in spring and after bloom. I can't worry about "weaving" the shoots laterally or trimming off possible potential flowers.(Tough love) I tie selected new branches with twine(upwards to cover arch and along sides to cover frame of trellis). He goes into winter neatly-like now, with attention to "scragglers" that want to branch out. I carry "nippers" frequently and use them to keep him from getting messy. I have a small ladder to access the top 1 or 2x a summer.He comes back full of blooms springtime inspite of frequent "haircuts". As Karl bapst rosenut says JC is vigorous and will keep you busy.(!) But I love him. I prefer a heavy, strong grower after losing my first 2 choices in this spot. He is 4 yrs old.

Thank you Karl for your information on William Baffin. I have not visited the Rose Forum for some time since I do not have near as many roses as in the past because I got tired of fighting blackspot and Japanese beetles. I was pleased to see you responded since I recognize your name from the past, and I valued your advice then, and now.

daisy, thank you for your great information. I am going with John Cabot. I figure he can take care of himself with my help, sharing the arch with a controlled Sweet Autumn clematis. I know it will mean some extra work, but I am willing to give it a try.

Jane

I was going to buy William Baffin about 10 years ago for an arbor and the nursery guy showed me a William Baffin on his property. It was a giant monster with canes all over the place. No trellis or arbor just a wide spreading bush. He pointed me to John Cabot. John's been pretty good, not as bad as that but still messy. I have him on a square style arbor and every time I try to train him, the canes fight me and don't want to be looped downward. I have had some good luck with pegging him along a nearby fence but I get a lot of dieback in the winter so every year is a new look. He has survived really bad winters and a tornado here in Minnesota and keeps on ticking, although not always in the best of shape. But I buy roses for vigor so I can't really complain.

Take a look at Ramblin' Red, cane hardy on the trellis in my z4 garden, good disease resistance & acts more like a climber...the Canadians you are looking at behave more like really large shrubs.RAMBLIN' RED @ HMF

My William Baffin was a much better repeat bloomer than my John Cabot. However. others (50-50?) reported the opposite. It was like there were 2 different versions of William Baffin in commerce.

I have prairie princess on a trellis too. She's also a survivor but more in the traditional form of a climber. She's not blooming yet or I would post a picture.