Instead of mirrors, I wonder if it would make sense to have greenhouses with artificial lights for winter and night. The original vertical farming idea was farms in buildings in the city. It has changed to focus on premium greens year round.
To solve the year round garden problem, it would be better to grow them in enhanced greenhouses. Then could use sunlight when available and LEDs the rest of the time for decrease in costs and increase in efficiency. There would be no improvement in land usage but even big cities have empty land nearby. I sort of think current vertical farming pivoted when original idea didn't work, but there is better way to do the pivot.
To solve the year round garden problem, it would be better to grow them in enhanced greenhouses. Then could use sunlight when available and LEDs the rest of the time for decrease in costs and increase in efficiency. There would be no improvement in land usage but even big cities have empty land nearby. I sort of think current vertical farming pivoted when original idea didn't work, but there is better way to do the pivot.