From what I've read, you would want to give them a big enough container (think a half-barrel), but one that you can take the plant out of in fall without disturbing the roots too much.

Also, if you have a bonsai society near you, they may be interested in harvesting your overgrown bushes. Neglected old landscape plantings often make excellent pre-bonsai.

Thanks. I placed an ad for the free trees and shrubs. There's some interest in them so that's great. I hate to kill healthy plants.

I have a couple of half-barrels but I'm not sure if there are drainage holes.

I have kept roses in large containers for a length of time and there were no problems. I've even overwintered them in the containers by sinking the containers into the ground for the winter.