Visit the
Library of Organic Information and you can look up how to treat lots of pests. There are several responses in the Fire Ant control category. I tend to use a bucket of hot water with dish soap, orange oil, and some liquid molasses in it. It kills some, annoys the rest, and they go away. Beneficial nematodes are good out in the yard. On your porch, you probably need to move the pot, not water it so much (they are attracted to wet spots), and I'd treat the area with any one of things that can annoy them (see the newsletters).