It is a beautiful plant but you will have a constant battle on your hands trying to keep it to one square foot of space. Eventually it will show up 20-30 feet from where you planted it.

Chazparas thank you for your response.

What if I planted it in a 3 gallon pot & put the pot in the ground? Think that would keep it contained?

Sand man,
I've only seen them grown and flowered successfully in very large pots, I mean huge! It will eventually escape from the bottom holes of a pot via runners. They really are beautiful vines, but a lot of trouble. Do a search on here for trumpet vine and see what comes up. Then make your decision. As much as I love the flowers of these vines I will never again plant one. Unless the seller is willing to give a written guarantee that they will pay for eventual removal of the plant. (how's that for dramatic!LOL)

OK, you have convinced me to pass on these vines. Got any suggestions for a part shade situation?

How much shade? Does it get any sun at all? Sweet autumn clematis will cover a fence like that in time and keeps a relatively small foot print. Also dutchmans pipe will cover a fence like that.

The area would only have full sun for around 4 hours a day. I already have 4 clematis plants in this area & they are having a tough time getting enough sun.

This variety is not as invasive as other trumpet vines. It grows to about 12-15'. Mine is in a 18" square container and it's only grown six feet in three years. You can contain it -- it's roots are not the double duty roots you'd associate with other trumpets, breaking through pots etc. -- but I doubt it will give you the 20' coverage. I am on year three and still waiting for the first bloom.

We have a sweet autumn as well. Much more vigorous in a smaller pot. Smells good too. Denser coverage.