I’ve never heard of that. I add used coffee grounds to my compost pile and I’ve used left over coffee from the pot to water plants indoors and out.

I don’t use anything as a preventative spray. I take care of insect and pest problems when they occur if necessary.

The things I have to watch for are: aphids, ants, cabbage lopers, squash bugs, tomato horn worms, cucumber beetles and grasshoppers. I use the common organic pest controls for them. I use Remay insect barriers for Cucumber beetles and grasshoppers