Here in sunny Florida, there are plenty of examples of efficient, indoor gardens. We call them grow houses. With supplemental CO2, mylar sheeting, and constant heat, they massively out-produce a normal garden.

But they're still not economically viable for any legal produce. Sun, dirt, and water are still too cheap in the Eastern USA.

With medical marijuana here, and full legalization on the horizon, I wonder how soon grow houses will be an obscure bit of history.