I'm using a cheap, plastic shelf "greenhouse" to harden my seedlings off, opening it during the day and closing it at night. I was hoping to start moving the tomatoes out soon since the plants are so large. Trying to find room on the light shelves is going to get difficult.

I'm not sure if the green house would be safe for them? It will protect them from frost but it won't be too much warmer in their at night, especially if it dips below 32 on a night here and there. So maybe I should start moving them out during the day and in at night?

The real problem with them is in the daytime when heat gets trapped in them if they aren't closely monitored and well ventilated. When the sun is out it can quickly get up to 120 degrees in one of them and cook everything.

But also keep in mind that it is a big environmental change for the plants so they will need to be hardened off first. They won't tolerate going 'cold turkey' right from the house into one of those units.

Be sure to include a thermometer inside it.

Dave