Be careful of the temperature, make sure its not too hot and the soil doesn't warm up too much. It will dry out the soil pretty fast and cook the babies if its too hot. You can get a laser thermometer at Home Depot for $10 - $15. Its perfect for checking the surface temp of stuff.Â
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I use a seeding heat mat and still find it a bit too hot, so I put a towel down over the heating mat, then put the seeds on the towel. A seedling heat mat is only supposed raise the soil temp 10 - 20 degrees above room temp, so play around with towel thickness to find the right temp buffer.