I first cut the canvas to the length of the pergola plus 6 inches.
I did not want to try to sew this on my home machine, so I used fusible backing that is used to make patches. I folded over 2 inches and cut the backing to fit, and ironed it. (follow the instructions from the manufacture). I used high heat and left the iron on it until the edge fused.
The top of the hem is where I started my measurements.