Commercial ant killer?
Here are some things you can try.
The cornmeal is the best way without using poisons. I only use the cheap envelopes of sweetened cornbread and muffin mix. I put it in a big spice container with a shaker lid and generously pepper the soil around the plants and/or the mound if you can find it. They take it for the sweet and die because they can't digest the cornmeal. Keep putting it on until you see no more and activity in the pot or mound. How many applications it takes depends on the size of their mound and the size of the ants. Some mounds may not look that big, but if there is a huge underground home to them, it takes more to feed all of them and kill the whole mound. This has really worked for me really well and I do recommend it since it is safe for all animals pets and humans, just not insects like ants.
It has worked for me, I just checked daily to see if the cornmeal was gone and if there was still activity. It is surprising sometimes how fast it disappears once they find it!