[ortho1121]

How do I attach a light fixture with a flat back to a curved column?

 

[Oso954]

You will most likely have to make your own mounting block with the back side cut to the radius of the column. I would then inlet the face of it to accept a pancake box.

Depending on how you are planning to wire it, you would need a hole thru the block, or combination of hole and a slot, to allow the wiring to be run into the pancake box.

 

[joecaption]

Got a picture?
Why does the light need to be on the column?

 

[ortho1121]

Each column forms an entryway to the backyard. No other site for the lights. Also, an esthetic thing.