I'm sprouting vegetable seed under lights this year vs using cold frames and heat cable. Spinach, broccoli, and some others are coming up in 2+ days vs 7-14. Is this OK? The lights are on 18+ hours to keep the seed cart warm. If this is not "OK" should I cover emerging seed with a little more soil or turn the lights off for longer periods; or not use lights at all. I'm using Lowe's Jiffy Pellet trays, flourescent lights ~2" above trays.