this will be rather hard to do. one motor, using pullys and gears, that is a lot for a motor.
you keep saying SERVO. if you are thinking $250 and another $50 for a power supply per row. plus the belts, pullys and such. you could get a SERVO to work.
check out some of these.
https://www.teknic.com/servo-comparison/
but you still need to design the mechanical bits.
based on the idea of 5 columns, I thing work gears on each tower, one shaft.
but, before I would open that door, I would try one out on a post like I show, just to test to see if rotating plants will yield more plants for harvest.
I an too far north to get such a project to work, but I would try to find some land you can use. unless you are using LED's at night ?
I'd also advise to look into hydropinics. pay for fish food, not fertilizer and the fish offer the fertilizer part. and at some point, you get to harvest fish.