I'm not sure that I see the need for this because almost anything can be grown in a container that's 25 gallons or larger, even if it might be happier in the ground. I think the comment field is perfect for this kind of information. If you're successfully growing a specific type of Crepe Myrtle in a container, for instance, tell us about it in a comment in the pertinent entry, stating the size of the container and explaining any special steps you take to keep it happy in a container.
