Persephone wrote:

What about a large pot where soil can be modified?

Usually they do best with a double pot with drainage holes in both pots.
The outer pot is to protect the inner pot from the sun. Direct sun on
the pot of an azalea can be bad, especially if the pot is not white.
Even potted azaleas do better when the pot is sunk in the soil to help
maintain even root temperatures and more even moisture. In the winter
in colder climates the pots must be protected from freezing.
--
Pardon my spam deterrent; send email to
Visit my Rhododendron and Azalea web pages at:
http://rhodyman.net/rahome.html
Also visit the Rhododendron and Azalea Bookstore at:
http://rhodyman.net/rabooks.html
Cheers, Steve Henning in Reading, PA USA Zone 6