start seedlings in a small pot, then gradually transplant into larger pots, this will encourage better root development. i say ur light is insufficient, and the temperature is not proper for growing. starting seedlings in a huge pot is not a good idea, it would be better to start off small. Also, get some fans to swade the little seedlings, this will make the main stem stronger. i suggest u get some bigger lights, along with proper ventilation, otherwise you wont get a satisfactory yield or quality.