You may plant minis anywhere you can plant roses. Whatever time it is for you to plant outside. They only look small and delicate, they're pretty tough roses. It won't stay small long. One grocery store rose I have in a pot is over 2'tall, might be even larger if I planted it and gave the roots unlimited room. I have other minis that are 5' tall and still growing.
Leslie

My experience with grocery store minis is that they don't seem to stay very mini. I bought 5 different ones: one of them, the most beautiful, developed powdery mildew within a week-I threw it out; after they were through flowering, 2 shot up very tall and scraggly but they were very healthy. They did flower again but they did not look as good as when I first bought them. When you buy a miniature rose on line, you at least get an idea of how tall they are supposed to be and if they will be compact or just "well-branched". You can never be sure about disease resistance.

where is a good source to buy minis? I mean the good ones like Bee Knees, etc. I got a decent one at Lowes. But I want to get some of the gorgeous ones I saw at the rose shows.

thanks!gbebeh

Nor'East have some very healthy miniatures, link at the bottom.
Also John's Miniature Roses.
http://www.johnsminiatureroses.com

Here is a link that might be useful: Nor'East

In addition to the vendors Leslie listed, add Rosemania.com, Bridges Roses and Almost Heaven Roses.