It's 42 today and sunny. Feels like spring. Too cold for the seeds I want to sprout, but they would benefit from full sun as soon as they start up, so I'll perch them on the back window ledge in my car. I'll have to open the window to keep them from getting too warm. I do this frequently when I need more space under the lights, and just to give the seedlings a better quality of light. If they've only been under indoor flourescents they can burn quite easily, so only a couple hours the first time, or until you know they're fine. They don't always show a sunburn until the next day, when they'll be white if they've gotten too much sun.