Sounds like you have a dry spot in your pot that does not "wet" when you water. I'm an indoor MJ grower but I grow other plants outdoors in pots. I find that when I get ants in my pots a good soaking and not letting the pot get dry takes care of them. The ants are not there to eat your plant, they think its a good place to make a home. The ants themselves can reinforce the dryness of the soil around their nesting area so make it a good soak. --- LTT