Greenhouse: Beginner with small tent unheated greenhouse ... questions, 1 by Tree_Climber

Tree_Climber wrote:
Hello All,

I have a small octogon, tent-like, unheated greenhouse.

I got it last year, but this is my first year when it's up and ready to use in early spring.

I am wondering when it would be safe to start using it for seedlings and some Dahlias I have potted up which have started to show growth.

We are starting to have more nice days than freezing cold ones, but our low temperatures still are near or even below freezing frequently.

Any help will be greatly appreciated.
I'm in Z5 MI ...