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Growing Organic, No-Till Hemp


Since the United States government legalized the cultivation and use of industrial hemp by way of the 2018 Farm Bill, farmers across the country have been scrambling to learn as much as possible about state and federal regulations, market and income potential, and detailed information on cultivation for this new and seemingly lucrative crop.

For organic, no-till hemp grower Andrew Mefferd, helping to introduce no-till cultivation methods to fellow eco-farmers is an important part of his mission to develop new varieties of hemp for cool, non-arid regions of the U.S.

While Mefferd is new to hemp (he grew his first crop just last year), he’s no stranger to no-till growing methods. Mefferd is the author of several books, including The Organic No-till Farming Revolution: High-Production Methods for Small-Scale Farmers (New Society Publishers 2019) and The Greenhouse and Hoophouse Grower’s Handbook (Chelsea Green Publishing 2017). In addition to editing and publishing Growing for Market, he also runs a three-acre organic farm in Maine with his wife, Ann.

Andrew Mefferd hemp
Andrew Mefferd and his hemp plants.

What Hemp Wants

When it comes to growing hemp — whether for fiber, flowers or seed — one of the first things that farmers want to know is, will it grow where they live?

“Hemp is a very hardy and adaptable plant,” Mefferd said. “But it doesn’t like its roots wet. In that respect, it’s more like a desert plant. Really wet or perennially waterlogged soils would be the only place you probably couldn’t grow it. But otherwise, hemp can be grown just about anywhere in North America.”

During his seven years as a senior trial technician with Johnny’s Selected Seeds, Mefferd did a lot of work with tomatoes.

“When I talked to hemp and cannabis growers, they repeatedly told me that they grew hemp like tomatoes,” he said. “The thing that stood out for me was how both have super resinous leaves and stems that coat your hands after working with them a while. So, if you’re familiar with growing tomatoes, approach the hemp crop like you’re growing a field of tomatoes and garlic and then get as nuanced as you want. It’s not that different and you don’t have to baby it.”

When it comes to soil fertility and hemp, Mefferd points to crop consultant Zach Menchini of Concentrates, Inc. Menchini recommends nitrogen at roughly 100 pounds per acre, potassium at 80 pounds per acre, and a surprisingly healthy dose of sulfur (sulfate) at 20 pounds per acre.

He also said that while hemp is a flowering plant, it didn’t necessarily need a lot of phosphorus, but rather potassium, which it removes at about 80 pounds per acre. To achieve many of these nutritional goals, begin by inoculating the potting soil for the hemp seedlings with endomycorrhizal fungi, which, when established, helps deliver nutrients and water directly to the roots of hemp plants. Mefferd also chose to fertilize plants in the field with concentrated fish emulsion and kelp extract once every week or two.

Insects & Disease

Mefferd said that aphids and botrytis were his two primary obstacles. “We had an enormous concentration of aphids followed by an explosion of ladybugs that took care of the problem for us,” he said. “It’s hard to say whether we over-fertilized and attracted them or not, but we’ve been organic for a decade and try to be kind to our beneficial insects — and they saved us.”

Mefferd said the most challenging issue they had was botrytis, also known as bud rot in hemp. This common fungal infection occurs in many vegetable and fruit crops and is spurred on by cool, wet weather in the fall as flowers and fruits are ripening.

“What’s happening here is a classic farming dilemma,” said Mefferd. “In hemp, the levels of CBD go up as the season gets later, but the susceptibility of the flowers also goes up as long as the plants are in the ground. We had a little bit of bud rot, but not a lot. We saw it right away and managed the harvest around it and dried it right away. If you let it sit in the field or dry it without good air circulation, the bud rot will just continue to flourish. But if you harvest the hemp and dry it out quickly, the fungus stops cold.” 

Mefferd stresses that a botrytis infection can turn into a disaster quickly if you are not paying attention. A little mold, caught early and dealt with appropriately, might have minimal impacts on overall harvest and income potential, and that certain CBD extraction processes can filter out small amounts of mold. However, he also says that if the infection is severe and prolonged, the entire crop may be useless. “This is one reason that growing hemp in rainy, humid northeastern and southern states can be a challenge.”

Market & Scale

Mefferd says that before growers even consider getting into growing hemp, they need to think about what their market is.

“Around me, it seems like everybody and their cousin grew hemp this year and we still don’t know what effect that had on the market price. It’s a brand new legal market and I think hemp is like the wild, wild West. We don’t have much of a track record for prices and other things like that,” he said. “So, before growers even think about how to grow it, they need to think about where they’re going to sell it.”

His first bit of advice in this regard is to get a contract or a written agreement from a buyer before a single penny is spent on seeds or supplies. This way, buyers know what to expect if they bring in a successful harvest.

“Here in Maine, we harvested around October and so did everyone else and the market was pretty weak. In this new wild West, a lot of money is going to change hands. Some are going to make a lot and some are going to lose a lot,” Mefferd said. “People get calculator happy and think they are going to get rich, but when the time comes, they lose more than they imagine. So, have an idea of where you are going to sell your crop first.”

Cover Crops & the Roller-Crimper

Mefferd said that small-scale organic techniques employed on a 1/4-acre worked well for him, but that growers looking at more than an acre should think about the roller-crimper method, also known as mulch grown in place. This method starts with a good cover crop that is terminated in place using a roller-crimper.

“The number one thing that many do wrong the first time around is to not grow a quality cover crop,” said Mefferd. “If they don’t fertilize and take really good care of it, or if the seed washes out after the cover crop is sown, they’re not going to get a good stand that will suppress weeds for the cash crop the following season.”

He said that rye and vetch are two good carbonaceous covers that produce thick biomass, but that any number of cover cocktails could be used. Of course, the purpose of a cover crop is to generate a thick layer of weed-suppressing mulch into which hemp seedlings are transplanted or seeds are sown. But before that can happen, the cover crop must be terminated and laid down. And depending on the type of cover crop, growers can use a mower or a roller. But for Mefferd, the roller-crimper does the best job.

“The metal fins lay down the cover crop and kink the stems at the same time, preventing the plant’s juices from flowing,” he said. “The best time to do this is when they are in flower when all the energy is in the upper part of the plant. First-time no-tillers sometimes try to roller-crimp their cover crops too early, before they flower and the crop survives and stands back up and keeps growing. But if they terminate after flowering has been going on for a while and the plants are setting seed, they are easy enough to terminate with the crimper but all you’ve really done is plant your own weeds.”

Mefferd hadn’t planned on growing hemp last year and wasn’t able to get a cover crop in before winter. Instead, he covered his 1/4-acre field with a combination of clear and opaque tarps to kill the weeds and grass and generate the first layer of mulch. Once the tarps were removed, he used a single deep-shank on the back of his tractor to rip transplanting furrows five feet apart on center.

You can use a transplanter or seeder, but they have to be set up or retrofitted for no-till. Mefferd followed each furrow with a 4-inch layer of compost on center and planted his hemp seedlings into that. Finally, hay bales were rolled out between the rows and around each plant deep enough to resist weeds.

Sowing & Spacing

Mefferd explained that spacing depends on whether you are growing hemp for fiber, oil, or seed and whether you need all-female plants or a combination of male and female. Other considerations should include the climate, disease and insect pressure, soil fertility, method of cultivation and the grower’s gut instincts.

Mefferd’s hemp was grown for CBD oil and seed that would be used as part of a breeding project.

“People who are growing hemp for CBD oil probably want all-female plants. In this case, using ‘feminized’ seed is the easiest way to go,” he said. “We were doing strategic pollination that didn’t include the entire field, so we started with ‘fertile’ seed, which means the seeds will produce a mix of male and female plants.”

Mefferd started his seedlings in the greenhouse and moved them to the field after all danger of frost. His initial 1/4-acre planting consisted of 600-700 seedlings with rows 5′ on center and 3′ between plants. In the end, 100 or more male plants in the field were cut out.

“I think if we were using feminized seed and didn’t need to cull males, we would have planted closer to 500 seedlings, which would be roughly 2,000 plants per acre. The way we did it made for a fairly tight canopy that reduced weed pressure.”

Mefferd has seen farmers whose spacing was extremely low-density, skipping every other row and every other plant in the row to increase air circulation to prevent disease. And while he sees the logic, he also notes that more open space increases areas that need weed management.

“That’s where you really need to have a plan in place early on,” he said. “Growing a great cover crop and rolling and crimping it down before planting is crucial in an organic no-till system.”

Mefferd doesn’t want anyone to think that what’s good spacing for him is right for everyone. The important thing is that farmers get out there and talk to their hemp-growing neighbors and local cooperative extension agents in their area to learn about what is or isn’t working for them and then decide.

Harvesting Hemp

When it comes to harvesting hemp, the scale of your operation can also be an important issue. With some help, Mefferd harvested his entire crop by hand and hung it to dry in greenhouses covered in shade cloth.

“It was a big job, but manageable. I’ve talked to growers with bigger fields that hand-harvested. You just have to have a method and handle it more quickly than we did. If you don’t dry it out fast enough, it gets moldy. But if you do it too fast, the plants lose some of their smell and oil content.”

Mefferd said that commercial-scale growers are using everyday chipper shredders, dairy choppers, and combines to grind entire fields of hemp into little pieces that are processed the same day at commercial extractors. Without being overly critical of the practice, Mefferd points out that large-scale harvest and extraction doesn’t distinguish between plant parts with high quality edible and medicinal oils and those that have little to none, like stems and fan leaves. He said that harvesting quality hemp by hand includes close observation of bud maturity to maximize the level of medicinal compounds without exceeding federal and state limitations of .03% delta-9 THC for dry plant matter. Anything over that and your crop is considered “hot.”

Mefferd said that the more mature the buds are, the more THC the plant is likely to produce. And, he said, if you grow hemp, you can count on inspectors coming to your farm and testing your crop. He insists that growers be ready to test their hemp regularly as it nears flowering. If THC levels are rising quickly, he believes that it might be better to play it safe and harvest the crop early, rather than be sorry and see the crop destroyed. Regardless of how you choose to handle it, understand the legalities of growing hemp and be prepared to test your crop and, if needed, to challenge official testing.

Mefferd said that he truly enjoyed growing hemp and plans to continue to do so in the future. This fall, he was able to plant a good cover crop for mulch and will be honing his no-till organic hemp growing methods next year, and for many more years to come.

Additional Online Resources

Andrew Mefferd, Growing for Market, Growing Hemp For The First Time? Here Are Some Guidelines On How To Fertilize, May 1, 2019, online interview with  Zach Menchini. https://www.growingformarket.com/articles/growing-hemp-for-the-first-time

Rodale Institute online, Choosing the Best Cover Crops for Your Organic No-Till Vegetable System https://rodaleinstitute.org/science/articles/choosing-the-best-cover-crops-for-your-organic-no-till-vegetable-system/

Connect Soil Health and Hemp

Join Acres USA for our 2nd annual Advancing Hemp event on May 20, 2021. This virtual event is designed to prepare farmers for successful hemp production through practical, applicable advice from industry-leading experts and growers. Learn more here.