Anywhere you could put a seed in my opinion! Be cpw apple seed! LOL I have grown and smoked great weed from outdoor and indoor grows! The only thing about outdoors is the uncontrolled environment and a bigger risk of pest, molds, and mildews but the free light is unbeatable! Don't have to run an AC either. Certain strains do really well outdoors and others do poorly outdoors. It also depends on the weather and region.
Check this out. Plant Doctor - Diagnose Your Plants! | Grow Weed Easy Maybe you can find your problem. I hope it isn't insect pest. I wouldn't spray my plants in flower with a pesticide. I don't think it is powdery mildew or mold. Are these outside? I saw where you said it was getting a lot of sunlight. Outside is the only place you get actual sunlight. If so, it could be pollen from all these flowering trees and plants. Everything in my area of the world is covered in yellow and white pollen. I wasn't talking about male cannabis plant pollen. Good luck figuring it out! Maybe that site will help you. They have about any question you need to ask covered on www.growweedeasy.com. Have fun and enjoy my friend!!