Hi Greene!
I get rosemary oil at health food stores (we have a little local place, but Whole Foods and similar stores carry essential oils and you can order on line). I've never measured, but typically use about 10 drops per quart of water with a few drops of dish soap. It has been a while since I've used it, but I'm pretty sure I avoided spraying in the hot sunny times of day- I typically spray in the evening. If I recall correctly, I believe I just used a mixture of my 3 go to ingredients- garlic, cayenne, and rosemary. The addition of rosemary made the concoction effective against hornworms.
