Last year with an overwhelming ant colonies in my garden, a huge quantity is Seven pellets were laid in the garden, especially the tomato section. After a week or so the tomato crop had an off taste and the county extension prep said better safe than sorry. So, in 2016 I lost the entire harvest. Has the past year been sufficient for the garden soil to be safe for planting? Would the poison be gone? What is safe to eliminate ants?
The only way to determine if your garden soil is clear and free of the chemical Carbaryl, the pesticide that is in Seven, is to have the soil tested.
Contact the County Extension Office to see if they can help with a soil test that can test for pesticide traces.
If they do not preform these soil tests, they may be able to refer you to a lab in your region.
I did locate the link below that gives all the Pesticide Information Profile for Carbaryl.