Tea roses can keep on getting larger even after five years, but I think you can do some gentle pruning and shaping on the more vigorous ones after three years, if they need it. If not, I'd leave them alone. The best thing you can do for them is allow enough room for them in the first place, which of course I didn't do. It's so hard to believe that little runty thing will grown so big. But it does and it will.

Some roses may be disease-ridden in your area or may not like the heat, and I wouldn't wait three years to toss a rose that's constantly covered in rust. However, tea roses for instance can withstand disease much better after they've put on some size so sometimes it pays to be patient. It might not be a bad idea to leave some of the smaller roses such as polyanthas in large pots to see how they do for you or whether you even like them.

"How Long" will be greatly-affected by climate. Here, where it's usually cooler, things take longer. So that answer has to come from someone who knows your conditions.

And, FWIW, I've seen many Teas mildew in immaturity, but outgrow the problem in maturity.

A rose that rusts, however, does not seem to outgrow that weakness.

Jeri

Thanks! Thus far, I haven't had any problems with mildew and rust. Just late season blackspot. My Buff Beauty is close to three years old and growing at a glacial pace...but I have faith in her.
Lav Lassie will turn 3 next spring and I'm hoping for an explosion of bloom. Lots of cane growth this year but very sparse bloom.
Susan