Last year, Brown signed into law a system that will regulate, license and tax those who grow and sell medical cannabis. But a mistake in the bill's drafting set a March 1 deadline for cities to either adopt stronger rules or face living with the state restrictions that allow cultivation.
As a result, nearly 100 cities have banned commercial cultivation, the sale of marijuana or both -- mostly in recent months -- according to industry officials.
Among those that have enacted cultivation bans are Burbank, Pasadena, Thousand Oaks, Yorba Linda, Long Beach and Newport Beach. Some counties have also banned cultivation.
On Wednesday, Brown signed a bill that eliminates the deadline.
"The governor supports allowing local municipalities a reasonable amount of time to come up with regulations that work for their communities," said Deborah Hoffman, a spokeswoman for the governor.
Eva Spiegel, a spokeswoman for the League of California Cities, said the action would allow local officials to revisit the issue and potentially make changes in their ordinances.
Supporters of medical marijuana urged cities to act.
"We are calling for locals to repeal the bans in favor of meaningful land regulations that will enact the statewide licensing standards … in order to protect public safety, the environment and patients' rights," said Ellen Komp, deputy director of California NORML, a cannabis legalization group.