growing in cold soil

I started my seeds in cold soil and its almost been 4 days now and all six plants are almost 2 inches and was going to transfer them to their own pots but like i said they are in cold soil right now and growing just as fine as the ones i have in regular warm soil. My question is since I haven't seen it hurting the growth should I keep growing them in cold soil or transfer them. If I transfer them how would I heat the soil that they are in now without hurting them since they are almost 2+ inches already. Any input would be appreciated. Thanks