i wanna grow in my backyard (it's pretty safe from detection) but there is a street lamp like 3 yards from my grow spot. will it hinder flowering? there is another spot with no light from street lamps but that is closer to the sidewalk edge of the fence. thanks.
Yes. It WILL cause problems with flowering. I suggest moving to the other spot and keeping your plants short with topping/LST and you could maybe keep it stealth.
From experience, I have to disagree with Socks. I live in a (mostly) urban area with security lights as well as streetlights all around. I have not noticed any adverse effects. I believe the lighting is based on what the plant is used to. If it is used to pitch-black nights then a street light might mess up the plant's circadian rhythm but if it is grown with light pollution during the dark period, I think it just adjusts to the less than dark nights.
Agree with OldSkool, the plant will be used to it. I dont think you gotta worry much about any light leaks outdoors. Indoors people worry about it, if the plant is used to completely dark nights and then gets a shot of a light when it normally doesnt the plant might hermaphrodite. Outdoors not a problem because that street light will be on everynight.