I have not read the statement, but it is true that gallicas on their own roots don't like to be confined. Their tendency to spread aggressively could cause them to exhaust the soil of the pot that contains them. Then they would start to decline. However, I don't think it is a problem with a young plant that has not yet started to wander.

I personally am not aware of anything that would make pots a bad idea for grafted gallicas. Perhaps someone else knows more about this.

Rosefolly

Zaphod42, I always put gallica bands in pots for several years. I begin with a 1 gallon and move up from there until the plant looks ready for survival in my chaotic garden. Three years maybe? Rosefolly's info regarding own-root gallicas in pots for extended time is what I have heard, too. However, I have also broken the rules and grown smaller own-root gallicas longer term in very large pots. I do change the soil in time, I do trim stolons, and I do feed and water well. You can root prune them like trees in pots. Fogrose may have some gallicas in pots, too. She's battling tree roots and grows potted roses. Maybe she'll chime in if she has experience with gallicas. I have a Lady Banks in a big pot, too. Once again, not recommended I'm sure, but mine has grown there happily for years! Hope this helps. Carol