PORTLAND — Visitors to Deering Oaks on Saturday may take in a little more than fresh air.

The park will be the venue for a free medical marijuana rally and festival featuring speakers, music and vendors selling indoor growing equipment.

The Atlantic CannaFEST will run from 1 to 5 p.m. and is expected to draw 200 to 300 people. It will promote medical marijuana and include a high-profile giveaway of pot to low-income patients, to protest the prices at state-sanctioned dispensaries.

So far, city officials, police and parents who use a nearby playground are treating Saturday’s pot rally as just another day in the park.

“It doesn’t bother me any,” said Ashley Van Vliet, 21, of Westbrook, who visited Deering Oaks on Tuesday with her 3-month-old son and 2-year-old daughter.

Maine is no stranger to marijuana festivals. Harry Brown’s Farm has hosted pro-marijuana festivals in Starks since 1991. Last year, the Augusta Civic Center hosted a medical marijuana expo put on by the Medical Marijuana Caregivers of Maine, which featured an outdoor tent where registered patients could smoke pot.

There will be no such tent Saturday in Portland, because fire codes don’t allow open flames in tents, said Atlantic CannaFEST’s organizer Charles Wynott, a 48-year-old Portland resident who uses medical marijuana to treat his AIDS symptoms.

Use of medical marijuana has been legal in Maine since 1999. In 2009, voters approved as many as eight medical marijuana dispensaries statewide.

Qualifying patients can possess as much as 2.5 ounces of pot in public. Although state law doesn’t allow people to smoke it in public, Wynott said it will inevitably happen Saturday if 200 to 300 people show up.

“We’ll try to keep it out of the public eye,” he said.

Portland police don’t plan to have extra officers on duty Saturday and will not have additional patrols in the area, said Assistant Chief Vern Malloch.

“We depend on voluntary compliance from the public for all laws,” Malloch said. “We don’t have any different expectation here.”

Medical marijuana is illegal under federal law. The Maine Drug Enforcement Agency did not return messages left by email and voicemail Wednesday. U.S. Attorney Thomas E. Delahanty II could not be reached for comment.

Rep. Mark Dion, a former Cumberland County sheriff, and Rep. Diane Russell, who last year introduced a bill to legalize marijuana, are scheduled to speak at Saturday’s event.

Ten to 20 vendors will sell their wares, including marijuana growing equipment such as lights, tents and soil, in 10-foot-by-10-foot tents.

Wynott said the event is intended to connect medical marijuana patients to caregivers and rally against proposed new requirements for growing marijuana, including limits on the number of nonflowering plants, property line setbacks and 8-foot-tall fencing around plots.

The comment period for the proposals closed last week, said John Thiele, director of the state Department of Health and Human Services’ medical marijuana program. The agency is reviewing the comments, and it’s not clear when new restrictions will be enacted, he said.

Saturday’s event will also call attention to the prices charged by some dispensaries.

Chris Kenoyer of Portland, director of the Maine Patients Coalition, said he plans to protest the high price of medical marijuana by giving away “a couple grams” of high-grade pot to 25 patients.

Patients can legally give away extra pot as long as they are not reimbursed, Thiele said.

Kenoyer, 54, who suffers from an inoperable degenerative spinal injury, said the pot will be given away by raffle. He hopes to conduct the raffle from the stage to highlight the lack of access for low-income patients, but Wynott said that likely won’t be allowed.

Anyone who enters the raffle will have to show their state ID, doctor’s certification and proof of low-income status with a MaineCare or EBT card, Kenoyer said.

Kenoyer said Wellness Connection of Maine, which operates four of the eight dispensaries in Maine, charges as much as $400 an ounce and $20 for a single pot brownie.

Becky DeKeuster, executive director of Wellness Connection of Maine, said Kenoyer is “flat-out wrong” about the prices.

“I’m sure it’s a misunderstanding on his part,” she said.

The dispensary charges around $300, she said, and is starting a program to help low-income patients, providing marijuana for as little as $100 an ounce.

“We are aware that many of our patients are low-income and this is not covered by insurance,” she said.

Wynott said he tries to help low-income patients grow their own marijuana and connect them to caregivers.

Maine has 766 registered caregivers, each of whom can grow for as many as five patients, Thiele said. It’s unclear exactly how many people are using medical marijuana, because the state no longer requires patients to register.

The Deering Oaks bandstand is about 50 yards from the William A. Goodwin Playspace in the park and about a tenth of a mile from King Middle School and several athletic fields.

Veronica Dulac, who went to the park Thursday with her daughter and the daughter’s friend, said she wouldn’t feel comfortable bringing the 6-year-old girls to the park if the rally was going on.

“It might be a bummer for families coming here, not anticipating” a pro-marijuana event, said Dulac, 30, a nursing student at the University of Southern Maine. “I hope they do it in a respectful way.”

Doris Jackson, 39, of Scarborough said she has mixed emotions about the event. She believes in personal liberty, but doesn’t support the use of medical marijuana. If she came to the park during the event, she said, she would use it as an opportunity to talk to her 9- and 6-year-old sons about the issue.

Alex Feldbauer, 24, of Windham, who brought his 2-year-old son to the park, said a pro-medical marijuana rally wouldn’t bother him.

“This is a public place for this specific purpose — that’s why there’s an auditorium over there,” he said. “As long as people aren’t bringing their children over there.”

Mayor Michael Brennan said he expects organizers to follow the laws and the rules outlined in their permit.

Police have typically shown good judgment and discretion in enforcing the law, Brennan said. “I hope they will do that in regards to this event.”

Wynott said he would like to make CannaFEST an annual event, but Malloch, the assistant police chief, said future events will hinge on people’s behavior Saturday.

“I think if people want to engage in civil disobedience and publicly smoke marijuana, we will respond,” he said, noting that smoking pot in public is a civil offense. “I’m not sure it furthers their cause, but that’s for the individual to decide.”