The "Average Date of Last Frost" is approximately around Tax Day. Keep in mind this is the 50/50 point. Our area has is prone to last frosts as late as the first week of May! If you choose to risk it and plant in ground now, just be prepared to cover with fabric and keep an eye on night time low temps.
Tip of the day: Need to replant a dead tree? Replacing with the same type of tree may not be the best idea. Ask...