Welcome to the world of greenhouses, Rubi.
An unheated, or stored heat, greenhouse cools down just about as fast as the outside temperature. A greenhouse without shade protection and proper ventilation will heat up very fast once the sun hits it.
Unfortunately, no one who sells them tells you that! It is a steep learning curve when mastering greenhouse growing. Think of it as a challenge and opportunity to learn more.
@jpm995 Doesn't matter much if it's small or large, they heat up fast without the adequate safeguards.
