It just depend which plants you intend to grow, like anything else.

I usually plant mine in gravel without aquatic soil, in the typical aquatic plant pots. I have tied rhizomes in with clear fishing line if they are in danger of floating free. I have many different plants. I do have fish and newts as well as invertebrates in the pond and they provide nutrients from their waste products.
if you do go down the terracotta pot idea don't plug the hole just use gravel as you need 'water movement'.
rinse the gravel to remove any dirt etc as you would if you were using it in a fish tank.