PROVIDENCE — Rhode Island has issued emergency regulations to begin licensing a new group of private growers of medical marijuana.

The Department of Business Regulation said creating a new class of marijuana cultivators will protect patients from an expected shortfall of the product this winter.

The regulations took effect Tuesday.

State officials said there could be a shortfall of medical marijuana after a new law takes effect on Jan. 1. That law bans patients and their caregivers from selling their excess plants to dispensaries.

In Rhode Island, licensed dispensaries are allowed to grow marijuana as medicine, but patients and their appointed caregivers can also grow their own plants.

Caregivers are supposed to grow enough for their patients to use, but some had been making big profits selling large amounts of the drug, said Norman Birenbaum, the state policy analyst who is helping craft the new business regulations.

"They've been incentivized to grow well over what they need and what the patients need," he said.

The new rules taking effect next year are meant to stop that. But dispensaries that distribute marijuana to patients also had come to rely on those caregivers for their supply. The emergency regulations are needed to prevent patients from turning to the black market for their medicine, Birenbaum said. It gives aspiring growers time to seek licenses now and begin growing the crops that can be harvested next year.

The emergency rule speeds up the process of licensing professional cultivators who can grow, process and package plants.

The changes are part of Democratic Gov. Gina Raimondo's broader efforts to reform the state's medical marijuana industry. New rules approved this summer as part of the state budget also include a new medical marijuana tax requiring growers to buy tags from the state for plants they cultivate.