I have successfully grown dahlias in containers. The nice thing about them is that you can move them where you want them. However, you should use as large a container as you can muster. Mine were about 20 inches across and at least a foot deep. That way, there was room for the tubers to develop, they did not dry out as readily, and I could add lots of nice nutritious soil to them. I will use them again this year near my patio. You do have to water more frequently I found ( daily ), and staking is more difficult, thus the deep pot. Mind you, I had the 4 foot varieties in these large pots. If you are only going with the short ones, then staking won't be such a necessity, but you still have to be aware of watering needs.

Actually, I do not find it difficult at all to get the tubers up if planted in the ground. Just remember to use a large gardener's fork, and gently work the soil loose by digging and lifting about a foot away from the plant. Then get your hands into the soil and gently lift the plant, tubers and all. When up, then you can trim the stem back.

Take some photos and post for us all to enjoy once you have them in bloom.

A good place to find out about container gardening is Steve Nowotarski's site- lots of good container dahlias, how to grow them, care for them & some pretty mixed containers to give you lots of ideas & some cool dahlias to look at in the middle of winter!

Here is a link that might be useful: container gardening