Pfg wrote: I potted my tomatoes up on 4/16, some into 16oz Solo cups, some to 1 gal pots, planted deeply with only the top leaves showing so they can grow roots along the stem. They have been outside in this unheated mini-greenhouse ever since. I filled 2 1/2 gallon bottles with warm water and put them on the bottom shelf to absorb heat during the day and keep the temp up a little at night. When I'm there, the zipper is opened during the day so they don't cook, and closed at night. When I leave, I attach a piece of row-cover fabric over the opening with clothespins, open the zippers and leave the door down loose. When I put them out, night temps were in the mid-40's, day mid-to-high 60's. I was gone for 10 days when I had expected to be away only 3 days, and got back in time for the cold spell over last weekend. Mini-maxi thermometer in the greenhouse showed 35/82 (during the day it heats up fast once the sun is on it). At that point the plants had grown about 3", the stems were thickening, and they looked quite healthy.
Over the weekend, outside the lows were in the mid-to -high 20's in the area, but my outdoor sensor, sheltered on a house wall, showed 32. The miniGH (door zipped closed) showed 35. Highs were mid-50's. My tomatoes looked fine. Luckily the weather improved just as I had to leave again, so it was safe to unzip the door again. I'm still a few weeks away from planting out, by then they'll be ready to get out of the pots.