Effect of cold temps during seedling stage?

Cold temps will slow growth, but not really cause too many other major problems. As long as she/they are getting 5-6 hours of direct sunlight each day, they should be OK. If growth is slow due to the cold temps, obviously, your plants will require less feeding and less watering. From an earlier question that I saw in your diary, I have successfully grown plants in mid winter by having them outside during the day and putting them inside just before sunset to get a few hours under a LED light, before placing them back outdoors when I went to bed, so that they were once again ready for the morning sun outside. Just make sure they are protected from overnight frost. While the plants will grow, it will be slow and they will be somewhat reduced in size. It is a good way to grow autos outdoors, out of the normal Summer growing season, as they will flower with the extended indoor/outdoor light schedule and not be as upset as photoperiod dependant plants. Also makes for an easy way to try some strains out before committing to a full on outdoor Summer grow and a easy source of fresh buds out of season. Hope this helps.... Organoman.