TALLAHASSEE — Florida regulators faced a packed room of profit-seeking hopefuls and desperate parents Monday as they launched the first hearing on draft rules authorizing marijuana in the state for limited medical use.

The standing-room-only crowd came to offer feedback on a proposed rule drafted by the Florida Department of Health as it decides how to implement the law that legalizes marijuana low in THC (tetrahydrocannabinol) and high in CBD (cannabidiol) for patients with seizures, severe and persistent muscle spasms and cancer. The rules must be in effect by Jan. 1 and only patients who are put on a state-run "compassionate use registry" will be eligible for the drug.

After nearly seven hours of testimony and nearly 50 speakers, one thing became clear: Regulations will be key to determining whether the state's experiment with medical cannabis will go smoothly or become a series of lessons learned.

The law passed by the Legislature last spring authorizes five nurseries in each region of the state to cultivate and distribute marijuana for medical purposes. The draft rule proposed by the Department of Health envisions a lottery in each region whose eligible participants would include at least 41 nurseries that have been in operation 30 years.

Those ideas were roundly rejected by several commentators who warned that they fail to recognize the quality of technology, expertise and experience offered by various growers.

"If it's a lottery, the most qualified companies may not even apply,'' said Kerry Herndon, owner of Kerry's Nursery in Apopka who hopes to apply to run the nursery located in Central Florida. "I've put an enormous amount of energy into this already and, if it's a lottery, I wasted my time."

Other commentators warned that the law will create near monopolies for a handful of companies that could suppress price competition.

"Essentially you're creating not an oligopoly but a monopoly in that region,'' said Bill Pfeiffer, a former state administrative law judge now working for a group of marijuana investors. He also suggested that each company should be able to offer their product in multiple locations within a region and within the state.

"I think the Legislature has made it very clear they can offer it statewide or regionally as determined by the department."

Jennifer Tschetter, general counsel for the Department of Health, said there will be one winner in each region and each would be restricted to offering their products to customers exclusively in their region.

The families who worked to persuade a reluctant Legislature to pass the bill urged regulators to move quickly and carefully.

"We're really grateful we've gotten to this point,'' said Seth Hyman, of Weston, whose 8-year-old daughter, Becca, suffers from intractable epilepsy. "We watch our daughter suffer every day — yesterday she turned blue. We hope the state sets fair and realistic guidelines and, if they rush it, it's got to be done right."

The proposed criteria are strict: The plants must adhere to the formula of no more than 0.8 percent THC or less than 10 percent CBD — or all of the product would be destroyed. Growers must inventory their plants, cuttings and seeds daily or be subject to penalty. Chemical additives must be screened and carefully controlled and the entire operation must be under lock and key.

Twenty-three states plus the District of Columbia have legalized the use of multiple strains of marijuana for medical purposes. Florida's new law legalizes only a single strain, but the law is considered just the first step in bringing the plant legally to Florida because an amendment pending on the November ballot would allow for medical use for a much broader array of ailments.

Regulators hope the process they put in place this summer for the limited strain could be a blueprint for the wider law if voters approve it. It requires that a license will cost $150,000 and the grower must post a bond of $5 million. The investment also involves immense security and technology, and a requirement that growers fingerprint and screen their employees.

The law envisions growers becoming store owners, creating a series of dispensaries in each region of the state. The proposed rules suggest their stores be open at least 30 hours a week, and no later than 10 p.m. and the products they sell are limited: no edible cannabis products, such as cookies or candy, and no cigarettes.

The potential industry has already started a rush of businesses waiting to strike it rich on Florida's new crop. Some of the state's most prominent lobbyists filled the room, as well as growers from Israel, Colorado and California and farmers from throughout the state.

Representatives of doctors, investors and biotech specialists who also want to get on the cannabis train were in attendance, as was the mother of Charlotte Figi, the Colorado girl whose parents worked to first develop the low THC strain of marijuana for children with severe epilepsy.

Joel Stanley, the marijuana grower who developed the "Charlotte's Web" strain, urged regulators to be aware that the genetic composition of the plants are important to obtaining quality control.

"What makes Charlotte's Web particularly special is it does have that track record,'' he said. "We have eight different phenotypic expressions of the Charlotte's Web product . . . We choose to use the same one over and over again because we have found that others don't have the same level of efficacy."

He noted not all applicants will be equal and urged regulators to focus on those that are able to produce the strain more quickly and safely than others.

Stanley, whose company manufactures the low-THC extract through a nonprofit called Realm of Caring, is one of a handful of companies hoping to partner with growers in Florida to bring the product here.

State officials estimate that about 125,000 children with intractable epilepsy could be eligible for the drug and, if the constitutional amendment passes, 420,000 patients and 1,800 treatment centers would be needed.

Tschetter said at the end of the meeting that the department will consider changes to its rule and conduct a second workshop later this month to finish its work on the proposed rule.

NOTE: This article has been updated to include the following correction: Twenty-three states plus the District of Columbia have legalized the use of multiple strains of marijuana for medical purposes. Another figure appeared in an article in Tuesday's Times about Florida's new law legalizing a single strain.