Trevor Hughes

USA TODAY

COTOPAXI, Colo. – Down a long dirt road snaking deep into the yellow hills of southern Colorado, Ryan Griego and his staff are harvesting green gold: legal marijuana.

More than four months after they were planted, Griego's pot plants are finally reaching maturity, warmed by the sun and fertilized with fish and bat guano. Here, 1,000 organically grown marijuana plants are being chopped down, trimmed and processed for sale on Colorado's legal medical marijuana market. Griego's operation is one of the largest outdoor grows in the state, sprawling across a 40-acre compound patrolled by guards and watched by wireless security cameras.

Each plant is only about 3 feet tall, more bushy than stalky, but covered in prized marijuana "bud," or flowers. After being cut down, the plants are hand-trimmed to remove the biggest stalks, run through power trimmers that are also used to prepare hops, and then hand-trimmed once again. The buds will then be dried, tested for quality and potency, and packaged for sale.

It's a labor-intensive process reflected in plant's value: Each one is worth $4,000-$6,000, depending on yield. That means Griego's crew will be harvesting, on the low end, marijuana worth at least $4 million. And he's only one of hundreds of licensed growers across the state.

Much of the legal marijuana sold in Colorado is grown indoors under lights, which gives growers more control over lighting, pests and the soil. Outdoor growers can harvest only one crop a year, compared with three or four crops if grown under lights. But Griego says his organically grown outdoor plants will yield more and taste better when smoked.

"It's hard to mimic the intensity of the sun," he said.

Griego owns two marijuana stores, operating under the Cannasseur name, selling both medical and recreational marijuana in Colorado Springs and Pueblo. He'll use this fall's harvest to stock his stores for the year, and sell extra on the wholesale market. The growing season ends when frost begins nipping at the plants, turning their leaves yellow or purple. Plants that don't fully flower can be processed into edibles or marijuana oil for use in vaporizers.

Each plant is tagged with an RFID chip, allowing growers and state regulators to track its path from seed to sale. The plants are weighed after being cut down, again after being trimmed, and again when they're packaged for sale. Griego's dozen workers have all passed background checks and are licensed by the state to work in the industry that nevertheless remains illegal at the federal level.

"It's great to grow an American-made product, and that's what this is," Griego said.