You're doing perfect, as far as I'm concerned. Give them a good week or three in the greenhouse until your temps are stable in the 70's and then pull them out into the shade for a few days before moving them into the sun. As long as they have green canes, you'll probably see them just burst back to life. Once they are happy and healthy again, plant them just like a larger rose.

Don't expect them to stay small. Miniature refers only to bloom size. The plants can range from 12" to 3-4' in height, based on my experiences with 'grocery store minis', that is to say the Parade roses or the like that don't have individual names. If these have names, you will want to look up the varieties on HelpMeFind.com or ask here about them specifically, to get an idea of how large they get.

I have some perfectly beautiful 3'x3' minis that were un-named varieties. I have one that gets to 2' wide and about 4' high before I whack it back down to 1.5' again. Others have stayed about 1.5' x 1.5'.

Suz