If it's garden plants you can't just put some toxic pesticide in there. I have used boiling water before. It works well but is kind of a pain.
I have some strawberries in tubs and got a big nest in one of them. I walked into the barn and spotted some Chlorine pool tabs on the shelf.
These things stink right through the jug. I put one tab down into the hill and left it for about 3 -4 days. ( no rain) Ants left the premises and
I put the tab back in the jug. I hope this continues to work.

Wake up gardeners ! Spring comes right after Christmas.

Diatomaceous earth

Yep

Ants must love strawberry plants cause they always bedded in mine. I grow a lot of other stuff and strawberry is the only one the nest in.

I never thought about it but I think you are on too something. It was winter time and, I did some work on an experimental farm in Dallas County. He had different things growing through holes in plastic sheeting made of different colors. The theory is that when plants are growing through the plastic some plants do best with certain colors. But the section he had strawberries in was loaded with fire ants, I could barely walk through it without getting messed up. FYI he said strawberries do best with the white plastic and squash does best with the black plastic. Thats all I remember about which plastic the guy said does best.

I never knew that about the colored plastics, thanks

Diatomaceous earth has not exactly kicked ass. I collapse the structures every time, and hit the outside hill also. They have weakened somewhat though.
Fortunately this stuff is inexpensive.