Cities hope to rake in even more tax revenue from medical marijuana cultivation, which has remained in the shadows although it has been legal in the state since 1996.

Today, Oakland will begin the application process for four permits to run industrial-scale marijuana farms within city limits. In Berkeley, a successful ballot measure to allow medical marijuana cultivation in industrial zones has would-be growers scrambling to buy scarce real estate. Farther north, the Sonoma County wine country town of Sebastopol passed an ordinance last week allowing for the creation of two large gardens for medical marijuana dispensaries and two more “collective’’ gardens where patients could grow their own.

All this is taking place even though the state’s laws require any businesses in the medical marijuana trade to operate as nonprofits, and even though the amount of marijuana the cities are authorizing growers to cultivate could net a typical drug trafficker decades in federal prison.

California voters earlier this month rejected a ballot proposition that would have legalized marijuana for recreational use, but the already thriving medical marijuana industry shows few signs of decline.

The state’s loose standards for medical marijuana use allow Californians to easily obtain a doctor’s recommendation for the drug. Yet the law provides little guidance for how patients or their caregivers can legally cultivate the drug, which has forced growers underground.