My mini-greenhouse is caving in. Why? Can I prevent it?

Question

I am growing catnip in a minigreenhouse and the top plastic part is caving in. Does anyone know why? My boyfriend thinks it's due to lack of oxygen. Can it be prevented?

Answer 1

Lack of support?

Maybe you should reframe the support and reapply the plastic.  Unless there is a total and complete seal, there should not be a "vacuum" to cause it to collapse.  It could be that if it is sealed, that the pressure inside the building is less than the atmospheric pressure.  If that is the case, then install a vent to equilibriate the pressure.  As I do not know the dimensions, location, or other details, this is all I can offer.

I would not think the lack of oxygen would cause it.