May 15th - finally got all the plants in the ground. We waited this long because the nights had been in the 40's and this is the first point where it seems to be solid 50's at night for the next 10 days. I had excellent success with my seedlings, much better than last year, credit goes to heat mat and wrapping the plant stand in plastic with a heater in the room keeping temps in the 80's. Once the plants reached a point where I could begin hardening them, my husband suggested I turn off the heater so they could get used to 70 degree temps in the house which were closer to what they'd experience during the day once planted outside. I'd say they spent about a month in the super humid 80's environment and then 2-3 weeks re-potted and waiting to go into the ground. I thought I started my seedlings late by starting April 11th but it turns out to be perfect for this year.
I also had the incredible fortune of turning one purple sweet potato into enough plants that I did not need to buy any, but I had placed my order back in February to Filaree Garlic Farm so I called and asked them to switch it to Beauregard sweet potatoes. They couldn't have been nicer and made the switch so now I have to figure out where to put 12 more plants when they arrive.
The following is a photo of my purple sweet potato plants grown from one - just one - purple sweet potato! I may never need to buy slips again!