I don’t know what I’m doing . . . but it works, apparently. I leave space for the air and heat to be ‘exchanged’, when I create a little greenhouse cover. I never cover the plants completely. They have not overheated or gotten too cold. So far - so good.
I’m waiting for my tomatoes to have enough leaves and branches to ‘bury’. They are coming along - but not quite ready yet. Maybe another week? Next year I will start them a week or two earlier.
My vegetable garden space has a low stone wall surrounding it. I think this protects young plants a bit, when I first put them out. Maybe even creates a microclimate. Certainly it protects from wind. I put in an Early Girl and a Sweet Million, in hopes to have something a little sooner - and they look great. But, they have some growth on them - and Home Depot did the hardening off for me!
If it’s warm enough - I do what @northwoodswis4 does . . . take them outside for a daily ‘visit’ to the sunshine - and back indoors at night.
I collect rainwater all the time - (buckets and garbage cans everywhere - catching rain off of awnings and roofs!). I only water the seedlings with the rainwater. Maybe that has helped them. I have raw well water for irrigation, but there is nothing like rainwater!
@dimitri_7a what is the purpose of removing the leaves on the cucurbits? I have never heard of that.