I've been window growing and my plants are very strong..... If you have the right window and it's big enough and you rotate the plants they will grow just fine...... The glass will actually amplify the light intensity and thus give you more sustain in a shorter amount of sunlight..... plants will grow anywhere, they just might not grow to their full potential..... you probably won't get 6-foot plants growing in a window but I've seen people get very nice 3-4 footers with solid yield from a window grow......