In the interest of full disclosure, I have to show you the results of forgetting . . . to open your cold frame when it gets sunny and 60°F! I was preoccupied with garage saling for a couple of days. I came home, collected eggs, dug some greens for the chicks, grabbed a bite to eat, and out I’d go again! There were maybe a hundred sales going on in a one mile radius of my home—potent stuff.
The radishes seemed most affected. There was also some burn and wilting in the greens. I opened the frame and gave them all a good watering. I’m hoping that there is no lasting harm. If things bolt (go to seed), I’ll know the cause, chalk it up to experience, and replant.
I know there are automatic gizmos that will raise and lower vents in greenhouses and the lids of cold frames, but they are pretty pricey—well beyond what I can afford. It’s not a big problem since I am home most days. It also gives me an opportunity to watch everything grow! Begonia