Vegetable Seedlings If It Ok To Put Vegetable Seedlings Outside During The Day?

If it ok to put vegetable seedlings outside during the day? - vegetable seedlings

I started planting tomatoes and peppers 2 weeks. Now they are about 2-3 inches tall. I have an unheated greenhouse, and wondered if it was OK to put the plants in the greenhouse during the day is when I leave in the morning, in the 30s and when I was at home from the '50s. What is the minimum temperature, can withstand the seedlings? I live in Maine.