Mayor Eric Adams’ vision of erecting cannabis greenhouses on top of New York City’s public housing buildings has run into a significant obstacle: The federal government.

At an April 9 panel discussion in Albany, Adams said his team was exploring whether the city could allow cannabis cultivation on the rooftops of New York City Housing Authority (NYCHA) facilities. The idea, he said, would be to employ NYCHA residents to staff and oversee the greenhouses as the state continues to roll out its recreational marijuana program for adults.

Marijuana, however, remains illegal on the federal level, including in federally subsidized public housing, which essentially hamstrings Adams’ goal. NYCHA is deeply intertwined with the U.S. Department of Housing and Urban Development (HUD), which provides more than half the authority’s revenues through subsidies.

Olga Alvarez, a spokesperson for HUD’s regional office, said Adams’ office hasn’t yet reached out to the federal agency about the mayor’s idea for public-housing rooftops.

“HUD has not been approached on this issue,” she wrote in an email.

Asked specifically whether federal law would prohibit the cannabis greenhouses Adams envisions, Alvarez wrote: “There isn’t much more to say, marijuana is illegal in public housing.”

Adams’ comments came during a panel of Black mayors from across the state on issues related to New York’s legalization of cannabis. It was part of an annual, heavily attended conference put on by the New York State Association of Black, Puerto Rican, Hispanic & Asian Legislators — and came just a day before the mayor tested positive for COVID-19.

At the panel, the Democratic mayor discussed the challenges of cultivating cannabis in a densely populated metropolis like New York City. One way to circumvent that issue, he said, is by embracing hydroponic greenhouses on buildings throughout the city – including those owned by NYCHA.

“We want to examine the possibilities of having a greenhouse space on NYCHA rooftops to grow cannabis,” Adams said. “The jobs can come from NYCHA residents. The proceeds and education can go right into employing people right in the area.”

In a statement last week, Charles Kretchmer Lutvak, a spokesperson for Adams, said the mayor wants to ensure “those targeted by the ‘War on Drugs’ are first in line to benefit from the legal cannabis industry.”

But Lutvak seemed to acknowledge the federal hurdles to Adams’ vision for NYCHA rooftops.

“(Federal) laws still on the books continue to harm the same communities that have been targeted for decades,” he said. “The House passed legislation to this effect earlier this month, and we need those who are obstructing progress at the federal level to follow New York’s lead.”

The U.S. House of Representatives narrowly passed a bill April 1 that would decriminalize marijuana on the federal level and remove it from the list of controlled substances.

The bill’s fate in the Senate, however, remains unclear.