Pro-marijuana advocates were quick to call foul on Boston Mayor Marty Walsh’s warning that residents should prepare for 48 “pot shops” if the state should pass Question 4.

“If this law passes, 48 pot shops can happen in Boston in a very short period of time. There is no zoning in the law, that means there is no zoning regulation,” Walsh told Boston Herald Radio hosts Jaclyn Cashman and Hillary Chabot Wednesday. "The voters in Boston could do something to make some changes over time, but initially you're looking at 48 pot shops, they’ll be able to be placed in every neighborhood in the city.”

The ballot measure that would legalize recreational marijuana for people older than 21 also paves the way for dispensaries that could sell the drug. The new law would cap the number of marijuana dispensaries in each municipality at 20 percent of the number of liquor stores. In Boston, where there are 238 retail liquor stores, that means the city could see up to 48 pot stores.

But Yes on 4 spokesman Jim Borghesani said Walsh was using worst-case scenario scare tactics to influence voters.

If voters approve the ballot measure on Nov. 8, no retail shops would open until January 2018, Borghesani said. Licensing would open next October with preference given to medical marijuana facilities that are already fully licensed and operating under current law. Voters legalized medical marijuana in 2012.

“The reality of a full build-out quickly is just absurd,” Borghesani said in an interview with Boston Metro.

Cities and towns are also allowed to institute a lower cap through a referendum vote, according to the ballot.

“There would be time to do that,” Borghesani said.

There is already one medical marijuana facility open in Boston, Patriot Care Corp on Milk Street, which opened in August. A second dispensary, New England Treatment Access, has been operating in Brookline since February. Seven other nonprofits are currently seeking licenses from   Massachusetts Department of Public Health to open medical marijuana dispensaries in the greater Boston area.

Listen to Mayor Marty Walsh discuss Question 4 on Boston Herald Radio in the clip below.