This story could be a promotion of Showtime's "Weeds," if it had mentioned the series. My guess is the DEA isn't too keen on promoting a show that has a DEA agent ignoring the creation of one of these growhouses.

High-tech 'pot factories' popping up in suburban homes:

Like the others, the home on Elk Grove's Mainline Drive had been converted to what law enforcement officials call a hothouse, with 1,000-watt lights for growing and irrigation networks feeding high-tech hydroponic growing systems.

Walls and ceilings were smashed to allow for complex ventilation and air filtration systems that vented the telltale odor through the attic. A web of extension cords and makeshift electric panels illegally tapped into the outside grid to avoid detection and save thousands of dollars in power bills.
. . .
Until now, West Coast law enforcement agencies have been more concerned about large-scale outdoor marijuana gardens, which often are planted on public forests or park land by violent Mexican drug cartels. Those operations have caused increasing concern in recent years because they severely degrade the environment and pose a danger to people who wander across them.

The Drug Enforcement Agency reported a 50 percent increase in indoor farms last year, Taylor said. Those operations have several advantages: They can't be spotted by an airplane or hunter, and the plants also can be grown year-round.

There are other advantages. Beyond not being able to constitutionally observe under either the open fields doctrine or those allowing observation of a property's curtilage from the air or other publicly accessible viewing locations, there's another big one. In Kyllo v. United States, the Supreme Court ruled that observing hotspots of a house by way of sense-enhancing devices such as thermal imaging equipment was an unreasonable search under the Fourth Amendment. As a result, if you can keep power consumption low (and in the Central Valley, the best way to do so would be to install solar panels, I imagine) so you stay off the grid, without being able to meet the requirements of a warrant, law enforcement can't even observe the exterior of a home to see if it's emanating unusual amounts of heat.

I suspect that today, with more ready availability of thermal imaging equipment, they might find differently. Of course, who can ever tell. Fourth Amendment jurisprudence is all over the map, and you find yourself having to keep track of all of these random, disjointed rules.