What Soil Conditions Are Best to Grow Weed? Organic Cannabis Farmer Shares His Secrets

Medical marijuana is rapidly spreading across the country—most recently in Pennsylvania on Thursday when the state announced the launch of its patient and caregiver registry.

Patients should be able to obtain the medication by May, and more than 100 physicians have been approved to participate in the new program, reported the Associated Press. Even the FDA commissioner supports evidence-based research for medicinal marijuana products, though don't bring your legally purchased ganja to the airport.

But outside of legislative offices, there are thousands of farmers tending to nutrient-rich soil to grow all that weed. California alone grows 13.5 million pounds of marijuana annually, Bloomberg reported.

"It's very much like growing a tomato plant," said Stephen Jensen, owner of Green Barn Farms, an organic cannabis farm in Northeast Washington State. "They're a very hungry, energy-intensive plant."

At Green Barn Farms, the native soil is alkaline with an eight to nine pH level, according to Jensen. The growers bring in compost and organic materials to lighten up the soil and make it slightly more acidic in the six to seven pH range.

Though many growers will use special prepackaged soils made specifically to grow cannabis, Jensen's farm grows organic cannabis on a smaller scale.

"We want to grow it as naturally as possible—more like an organic farm product than an industrial grade product," he said. Once the pH levels are appropriate for growing cannabis, "we're ready to put the plants in the ground at that point."

"From that point forward, we're on a pretty rigorous feeding schedule."

The farm, which opened in 2014, composts teas to feed the soil and uses organic pellets from Be-1 Organics as a base to enhance composting. Then they water them weekly or even daily in the hottest parts of the summer.

Drainage is key for cannabis in addition to compost and aeration, said Jensen.

"They don't like their feet sopping wet."

Growing cannabis takes more than healthy soils alone. Similar to a rose plant, cannabis is susceptible to a variety of mite species, aphids, and caterpillars, said Jensen. His farm combats the pests using ladybugs, yellow jackets, and baldfaced hornets to keep the plants clean.

"You should attract those as much as you can," said Jensen, particularly if you want to avoid pesticides.

"If you're spraying any kind of pesticides on there, you're not going to be able to get that off your cannabis," he said. The plant cannot be washed the way a tomato or apple could.

The other option for growing is taking it indoors, which is a different process altogether.

Growing outdoors helps keep the soil nutrient rich, according to Spring Pot, a company based in California that sells fabric potting. The organic materials, earthworms, insects, and water allow the plant to absorb nutrients easily.

For indoor growing, Spring Pot recommends using nutrient-rich potting soil from a local nursery, or otherwise making your own. Keeping track of the pH, humidity, and nutrition levels indoors is also important.

"Any excessive amount of fluid retention may motivate yeast development, which usually could result in devastating damage," according to Spring Pot's recommendations. They recommend that indoor growers use vermiculite, peat moss, or perlite.