I planted my petunia seeds 2 weeks ago and there's a fair amount up but I was wondering if I should still expect more? And since their up I've been leaving the dome off during the day but I've put it back on at night when I've shut the lights and heating mat off because I have them in the basement and it just seemed a bit cool to leave them uncovered. But shold I leave the dome off at night too? This is my 1st time at started seeds so I feel very much like an amateur!
How to Grow Seedlings
You may get a few more seedlings but not many more at this point. Putting the dome on for cool nights is OK but probably not necessary. Petunias need lots of bright light. Put your lights on a timer and ON for 16-18 hours every day. The dome should not be on when the lights are on. Set the lights 2-3 inches from the seedling tops.