Good advice above.
Ants are attracted by a food source which is coming from two places, the soil (most likely) or your plants, well not the plants themselves but possible scale living on them and producing a nice sticky sweet residue ants just love. Look for little white, black dots or larger brown dots on the skin, those are scale and a feasting on your plants.
For a simple fix just buy 'Ant Sand' from Bunnings it's not the cheapest ($8??) stuff in the world for large areas but if it is just a few pots that will take care of them pretty quick.
The borax idea suggested above by diddi is a good one, Borax is quite safe to humans much more so than any pesticide.
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