Carrots should be in the Ground Now along with all other Cold Crops-broccoli, brussels sprouts,cabbage, cauliflower, beets, turnips. lettuces, Spring/Sticking Onions (Sweet Onions that are "Sets" Plants,May 15 or a little later).
Tomatoes and Peppers, normally all areas of Pa, Safe time for those 2 are May 15 or After!
Cucumbers, a little after May 15, closer to the end of may.
Melons, Even later, certain melons need night time temps to be above 60 degrees!
Pumpkins, depending on the amount of days per the type of pumpkin, last week of June to July 4, this makes them grow clear up to right before Halloween and gives you Longer lasting Pumpkins!