There are tons of plants that will tolerate your winters in containers, but what kind of plant are you thinking ... evergreen, blooming, herbaceous/woody, upright, trailing ... ? Do you want one you admire for its bark, it's winter form ... ? More help from you = more help for you. (I just made that up) Lol
Thanks joannabanana, Your "rule of thumb" is very helpful and gives me options.
Al, You are just tooo funny... In answer to your question and in an effort to help you help me : p ... Although I do like the occasional flower, I much prefer foliage. Evergreen would be good, blooming (not necessary, but JoAnna's suggestions of pansies and petunias have my ears perked), herbaceous/woody, upright, trailing would be great if I can have those things too? As I am still an amateur, in my mind, I was thinking that ANYTHING I put out there would die, so I decided to bring it to the experts (and look who arrived : ) ...for some great advice.
Mostly, I just want something alive out there that is not a 12 foot Ape!!! I much prefer plants...
I have this excellent book called "The City Gardener's Handbook". It talks about all sorts of plants suited to liveing year around outdoors in containers and planters on patios, decks and rooftops. It seems to be focused on a zone 6 & 7 ish climates, but the info is adaptable to any climate. The info in it might be very useful to your situation.
I'm going to look for the book. May be able to find a variation of it locally for my area. If not, adaptable is good and I'm sure if it will winter outside in zones 6 & 7, they will also be suitable for my climate. Thanks again.
Go to your library and get a copy of the book, it's excellent. I live in Zone 5b and used this handbook for my balcony garden. A lot of plants winter outside in my zone. Evergreens look better in the winter. Although plants can take the cold they usually go dormant in cold weather. But you've had good suggestions above, including the pansies which will bloom all winter for you. Good luck.
I assume you want blooming plants to winter outdoors in containers. In the deep South, pansies and johnny-jump-ups are the old stand-bys. They both can survive snowstorms, if you have one every 50 years or so. The latter is even more cold tolerant, and they are just covered with blooms. Snapdragons survive, but bloom more profusely when the temps warm up in late February. Then they put on a glorious display for several weeks. Ornamental cabbage and kale can be beautiful, but if you have a mild winter, and many of our winters ARE mild, they tend to bolt and don't develop their color too well. (If they do try to bolt, pinch off the bloom spikes immediately.) Stocks and petunias aren't going to work. Not in Alabama. I would also discourage you from using small trees and shrubs. Annuals are far more practical. Cyclamen are beautiful, not only the flowers but the variegated leaves, but they are pricey. They also need to be moved into the greenhouse or garage temporarily if the temps are going to drop below 30 degrees. You might check with your local Master Gardening group for more advice. Local advice is always preferable to that from well-meaning people thousands of miles away. Like politics, gardening is mainly local. I have the temerity to send this only because we have very similar climates in spite of the difference in miles.