A basic setup involves a wooden pole, a copper spiral winding upward, and a grounding spike or buried wire

https://www.scribd.com/document/1031077120/Electroculture-Greenhouse-Hacks-You-Can-Try-147606

A basic setup involves a wooden pole, a copper spiral winding upward, and a grounding spike or buried wire, positioned near crops to capture atmospheric ions and gently influence local electrostatic conditions.