I recall an article in the ARS magazine, from maybe 60 years ago, in which someone noted that the native Canadian wild roses suffered more winter cane damage whenever there was an unusually wet autumn. Evidently, the canes contained excess water and this caused them to split open in winter. In spite of this, I'm inclined to think that irrigation of roses, especially during a dry spell, is unlikely to cause problems. I think newly planted roses need to be watered and with their minimal roots it would be very unlikely that excess hydration occured.

Thanks Mike. That was my guess, too. Better to go into winter well hydrated... The climate here will suck the water out of them, anyway. It's a 'dry' cold, usually lacking snow cover.

Cheers,
Michelle