His is one of three medical marijuana dispensaries in Rhode Island, and his experience provides vital lessons for companies in Massachusetts that have won licenses to grow and sell marijuana. The first is expected to open in April.

Bock grows marijuana, legally, for a living, and the peril presented by just one small insect illustrates how difficult it can be to establish a thriving dispensary.

PORTSMOUTH, R.I. — A tiny spider mite is all it could take to cripple Seth Bock’s business.

For marijuana dispensaries, it’s never as easy as sticking a few seeds in the ground and watching the plants, and the profits, grow. “There are so many moving parts to this business,” Bock said.


The 12 companies that survived a withering licensing process in Massachusetts will need nearly hermetically sealed buildings to grow marijuana plants. The endeavor demands painstaking attention to heat, ventilation, and humidity levels in a sprawling cultivation building. Failing to do that can result in crop-destroying mold and mildew.

There also must be unwavering vigilance for pests, especially the dreaded spider mite, which can go from being undetectable to an infestation inside a week.

“They can float through the air on their own miniwebs, and they are totally [resistant] to virtually all natural pesticides,” Bock said. “In this region, they are the worst of the worst.”

Brent Vanzile, an employee at the Greenleaf Compassionate Care Center in Portsmouth, R.I., filtered hash oil used to infuse edible products with cannabis. Stew Milne for The Boston Globe/Globe Freelance

In Massachusetts, regulations require dispensaries to start their operations from seeds, not clippings known as clones, and to rigorously track each product from seed to sale. The rules, however, are silent about where the companies should acquire their first seeds — a sensitive subject, because marijuana is still illegal under federal law. That means transporting seeds across state lines, whether by mailing or driving them, is prohibited.

Dispensary owners say they buy from seed suppliers, and leave it at that.


A cultivator must be able to distinguish the sex of plants as they begin to flower, quickly weeding out the male plants to keep them from pollinating the females. Pollination decreases the crop’s quality and potency.

Figuring out which of the dizzying array of strains to plant can prove daunting. Some industry consultants speak of thousands of strains, though the precise number is unclear. Each strain contains a slightly different blend of chemicals, with some strains touted to ease seizures, or the spasms of multiple sclerosis, while others are advertised to reduce pain, or nausea, or eye pressure for glaucoma patients.

Leafly.com, a popular website that chronicles marijuana strains, lists roughly 1,200, and includes the genetics for each, along with patient reviews.

For dispensary cultivators, selecting strains is apparently as much art as science. Tim Keogh, chief executive of Coastal Compassion, a company approved for a dispensary in Fairhaven, said it can take months for a cultivator to pinpoint strains that pass muster.

They scrutinize the ratio of active chemicals in each strain, “the yield of the plant, how it looks, how it feels, how it smells,” said Keogh, who used to grow marijuana in Rhode Island and sell it to local dispensaries, something allowed in that state, but not in Massachusetts.

“It’s not uncommon for a cultivator in a year to try out 20 to 30 strains, and at the end of the year to have two or three new strains on the menu,” Keogh said.

Coastal Compassion is awaiting local permits to build its cultivation center and doesn’t expect to be ready to plant until September.


Given all the early complexities, one of the biggest challenges for the first Massachusetts dispensaries will simply be keeping marijuana in stock, said Bock and other industry veterans. Roughly 5,000 Massachusetts patients have already registered with state health officials and will be allowed to shop in the dispensaries, yet only one store, in Salem, is expected to open before summer.

Patients have been waiting for dispensaries since voters approved medical marijuana in November 2012.

“The difficult question is figuring out how many people you are supplying,” said Bock, whose Portsmouth dispensary, Greenleaf Compassionate Care Center, was the second to open in Rhode Island in 2013. “We never ran out, but there were days when I worried about it.”

The early medical marijuana dispensaries in New Mexico and Colorado did run out.

“The first year and a half we were open, we had trouble keeping products in stock,” said Kayvan Khalatbari, founding partner of the Colorado dispensary, Denver Relief, and a consultant to several companies that vied for Massachusetts licenses. “We got too busy, too fast.”

One of the biggest challenges for the first Massachusetts dispensaries will simply be keeping marijuana in stock. Pictured: The product at the Greenleaf Compassionate Care Center in R.I. Stew Milne for The Boston Globe

Alternative Therapies Group in Salem, the first company granted state permission in late December to start planting, is advertising an April opening, albeit with limited products initially, and by appointment only. The company’s chief executive, Christopher Edwards, did not return calls and e-mails.

Alternative Therapies Group is one of the 12 companies approved for a Massachusetts dispensary license. State health department spokesman Scott Zoback declined to comment on the potential for the first dispensaries to run out of products.


“It’s a brand-new industry,” Zoback said. “There are things we are going to discover as we go and part of that is patient demand.”

The second dispensary expected to open is In Good Health, a Brockton company that hopes to start planting in March and aims for a late June opening, said its cultivator, Jon Napoli.

The dispensary plans to offer about two dozen strains of marijuana, plus marijuana-infused food, known as edibles, and tinctures, he said. Marijuana products that are not smoked or inhaled through vapor are growing more popular, but the learning curve to create them can be steep.

Napoli doesn’t have the expertise, so he hired a specialist from Arizona, which opened its first dispensary in 2012. The process requires a complex method of extracting cannabinoids, the desirable chemicals from the marijuana plant, using solvents such as carbon dioxide, alcohol, or butane.

But there’s more. After extracting the marijuana chemicals, a specialist must purge the solvents, before a dispensary chef can use it for cooking.

“Getting the proper dose [in the finished product] is the tricky part,” Napoli said.

At Bock’s Rhode Island dispensary, it took months for chef Christine Reed to figure out the right temperatures and proportions when cooking ingredients in marijuana-infused brownies, macaroni and cheese, and other food. Too much heat can destroy the potency.

It’s also challenging to determine how much marijuana each patient should ingest to treat a specific condition, Bock said. Unlike federally approved pharmaceuticals, marijuana lacks large-scale, rigorous studies to show it works medicinally, and to establish widely accepted dosing standards.


“It’s trial and error,” said Bock, who suggests new patients at his dispensary try little portions of several strains to determine what might work.

Massachusetts rules require dispensaries to label each product with a warning that acknowledges the many unknowns.

“This product has not been analyzed or approved by the FDA,” the label is required to say. “There is limited information on the side effects of using this product, and there may be associated health risks.”

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