Several greenhouses are lined up next to each other at this private nursery.

Here is a view of the length of the structure. Not sure what the metal frame is for on the side - I am guessing this is mechanical support for the winds. The pipe coming up I'm thinking is gas, because exposed water piping would freeze. There is a vent-pipe at the left of the photo. I didn't see larger window-type venting anywhere else. The plywood is a patch? or mechanical support to mount internal items?

Another view. You see the door on the side, and can get an idea of the framing of the structure.

Plywood is consistent - must be a structure. Unit on end appears to be under construction.

Must be newly built structure. You can see the framework. There is a lot of metal. The skin is opaque and does not let the sun straight in. Not sure what all the tubing is, but the fans indicate some of it is electrical cabling.

This is the end unit under construction.

Looks like the horizontal rod rotates - Maybe the external framing is a type of venting.

Front view of the end unit.

Side view. These peaks run north-south. Underneath them is one huge room. You can see the venting at the top. Also appears to be a vent pipe on the end.

Inside. More elaborate trussing required for this large roof. Heavy unit seen supported in the rafters (looks like a heater).

Another view inside.

Closeup of the trussing inside the roof.

View of the 'heater' unit. Looks like a gas line running to it. Lights have electricity cabling. Not sure what the external unit is.

This is a simple structure on the end. Protects soil from the weather. If size is smaller, seems that the structure can be much simpler - although since the dirt is not as valuable it is not necessary to have such a durable structure.

Not a greenhouse, but it shows what's possible with some framing and a skin. Looks like this is also supported with positive air pressure within.

End view of the bubble.

The other end.

Several units lined up. These are more permanent structures, with brick foundations. They run east-west.

End view with cove entrance.

Side view. External framework clearly to operate vents.

Another view of the side. Large box must be the motor.

These are old units down on the end. Large fans are visible on the ends. Venting structures seen at the top. I don't think these are in use.

This unit on the corner of the lot is falling apart. The panels right where the structure curves look like a weak link. The new units don't have curved surfaces; only flat surfaces and sharp corners.

Closeup of the broken structure. Only the university units ran east-west. When private shops put up their own money, they choose north-south to go with the flow of the wind? .. may just be a coincidence.

Inside the broken unit. Framework appears strong. Still supporting heater in the foreground. Only the skin is compromised.

Inside view.

Closeup of the truss work.

I don't think this is a greenhouse. Looks like a garage - notice the large end door. The end panel is very sturdy and supports ducting and some heavy equipment.

Another set of elaborate greenhouses at NDSU. Foundations are brick.

Apparently vents are at top. The side units must be condensers for airconditioning - individual units for interior rooms.

The glass is very thick. Not 'opaque' but still can't see straight in.

Plants

End door to a central hallway.

Central hallway.

Interior plumbing. Temperature kept warm so that pipes don't freeze.

Front facade of greenhouse built with structural integrity to hold front door and windows.

Closeup of front corner. Sides are made of plastic held down with wood slating.

Side view. Not sure how the roof is constructed; it has a curvature.

Closeup of side.

Back end. You get a view of the internal framing. Looks like stove pipe on the outside - supported by plywood, and separated from the plastic. Framing material is wood.

Closeup of back end.