Is your greenhouse unheated?
I built an attached greenhouse/foyer last fall and love having the warmth and sunshine. On a sunny day it heats the whole house just fine.
But it drops down to near the outside temps at night.
Kinda leery to use it to start plants.
yes it is currently unheated. don’t really need heat, however, if temps drop to freezing i can put a small heater in to prevent damage. We start the seedlings in the house to sprout them, then we transfer to the green house to toughen them and give them better sunlight.