It's already been done (LEDs for growing weed, impossible for cops to spot growhouses using FLIR helicopters and much lower power usage so spikes in energy consumption are far less dramatic).
I think in terms of impact, growing vegetables in a sustainable manner that uses little water will be critical for the long term sustainability of cities where water is scarce, such as Dubai or other cities in desert regions.
Some people in that market are already seeing harvests equal to 1gram per watt on LEDs. And the quality is as good as a much hotter high-pressure sodium bulb of higher wattage.
I think in terms of impact, growing vegetables in a sustainable manner that uses little water will be critical for the long term sustainability of cities where water is scarce, such as Dubai or other cities in desert regions.