Actually my very first attempt at germinating seeds a while back involved this window sill method. I had absolutely NO lights. And that was the first week of April, in central Ontario. It was chilly outside. Used the ziploc bag method to germinate. Then I properly planted the germinated seeds into Jiffy peat cups, and placed them on a window sill in one row (facing sunlight for most of the day). All of them turned out great. A bit stretchy, and they slightly tilted towards the sun throughout the day, it was actually entertaining. In the morning they would lean on one side, in the evening on the other side. Very neat. Then they got too big and I had to give them to a friend because it was too cold for transplating them outside, haha.