Marguerite Bolt, hemp Extension specialist at Purdue University, said growing hemp is much like learning to grow other crops – there’s a learning curve.
Many established growers and first-time farmers became interested in growing hemp after it was legalized in the 2018 Farm Bill. However, some newcomers to the crop were quickly weeded out. “There was a big shift in the value of a hemp crop after the 2019 season,” said Bolt. “That continued up until now. Some people went into it with expectations of big returns from the crop – they put a lot of money into production and it wasn’t economically feasible for them to continue into the 2020 growing season because the value of CBD hemp dropped.”
Although hemp can be quite profitable, Bolt cautioned potential growers to not view hemp as an easy crop they can simply put in the ground and wait until it produces. “People who go into it realizing it’s a new industry with challenges tend to do well because they’re going into it with an open mind and being realistic,” she said. “It’s a new industry and we’re all learning together.”
For first-time hemp growers, Bolt suggested spending at least nine months developing a plan for the next growing season. Visit hemp farms, work with local Extension, visit vegetable farms and consider other crops that might work with a hemp rotation. Growers should develop a five-year farm management and production plan to be fully prepared.
Soil testing and weed management prior to planting is important when fields are prepared. Any existing perennials in a pasture or field will become weeds in a hemp field. “Think about weed competition between hemp and what was previously grown,” said Bolt. “You might till it and it looks nice, but there’s a good chance there are seeds in the soil that will germinate. Some growers grow on plastic; some grow on raised beds and maintain a mowed cover between rows. It’s also important to control competition around the plant.”
Growers who incorporate plastic and drip tape can supply water to plants during dry conditions. During a wet year, there’s enough natural rainfall but excess rain can invite disease. Irrigation provides assurance that plants will have adequate water, especially early in the season when the root system is developing.
Plastic helps preserve moisture, but growers must deal with used plastic at the end of the season. Bio-compostable “plastic” may be a reasonable alternative. Growers should consider the cost of purchasing a bed shaper that will also lay plastic and irrigation tape. “Equipment considerations are important for this crop,” said Bolt. “If growers to want to grow vegetables, they can use the same equipment for multiple crops.”
Crop diversity is important in the case of crop failures, and most vegetable growers already have the equipment necessary for growing CBD hemp. “The biggest challenge with cannabinoid production is harvest,” said Bolt. “It’s very labor intense and time-consuming.”
CBD hemp can be grown from seed or cuttings (clones) from mother plants. Mothers are grown through winter under controlled lighting to prevent flower development, so consider energy costs. The problem with clones is the need to maintain mother plants large enough to supply enough cuttings for a crop. Growers can work with a greenhouse that produces cuttings or contract with an experienced grower to start seedlings.
“It’s easier to start seeds than growing a large mother plant for cuttings,” said Bolt. “Cuttings tend to be a bit more expensive than seeds or seedlings.”
Hemp seed is produced in Oregon, Colorado, California, Wisconsin, New York and the Carolinas. “If more people are working with specific producers, more CBD performance data information is available,” said Bolt. “People can seek out specific genetics based on information online.”
Although West Coast genetics do well in the Midwest and Northeast, growers who select strains from certain areas probably have an advantage. The issue is determining whether there’s good data available on local genetics. For example, if a Colorado seed company has been breeding consistently for five years, seed may have more reliable genetics and less risk.
Many CBD hemp growers choose organic production for its added-value benefit. Another reason for organic production is the lack of pesticides labeled for hemp. “There aren’t as many transitions to be made for a hemp crop to comply with organic management practices because growers already have limited options,” said Bolt. “For folks who are already interested in organic production, this is the catalyst that pushes them into organic. We’ve also seen people use hemp as a way to transition to organic.”
Integrated pest management is a critical aspect in any crop production system, but especially with the unknowns regarding potential pests and diseases in hemp. Growers who aren’t certified organic can use organic management methods for transition to organic.
Bolt said corn earworm seems to be the worst pest issue for growers, but researchers are working on the problem. Corn earworms are especially challenging because they burrow into plants and remain out of reach of sprays. “Some of the organic products provide good control for corn earworm,” she said. “Using a mix of products that have different modes of action is one way to deal with corn earworm. Some growers with small acreage simply pick them off by hand.”
Corn earworm has many different host plants and will be present in nearly any area where cash crops are grown. Some viruses attack corn earworm without any product applications, which is a good indication that supplementing the virus will kill more caterpillars without killing beneficials.
Many natural enemies provide protection for hemp plants. These include parasitoids, insects, predatory mites and spiders. Tachinid flies that attack corn earworm are especially helpful. “We see flies lay eggs on the corn earworm and parasitize them,” said Bolt. “We aren’t releasing these flies – they’re already in the environment. It’s exciting to see natural pest suppression occur out in the field.” Scouting is important, and growers should track observations to determine when to apply products.
In addition to scouting for insects and disease, growers must scout for male plants and promptly remove them. Plants grown from cuttings should be 100% female, but with seeds, there’s a possibility of finding a few males. Males begin to produce pollen sacs, which make their presence obvious, or growers can send clippings to a lab for sexing. Bolt said genetics are becoming more consistent and it’s easier to identify male plants when they’re young. For plants transplanted in May or June, pollen sacs should appear in July.
Air flow is important for cannabis. There’s less concern early in the season when plants are small, but plants will become large. Adequate spacing and pruning will help reduce foliar diseases. Some foliar products used in organic production of other crops are suitable for cannabis. Flowers require good airflow and sanitation to reduce disease pressure, especially later in the season when bud rot (botrytis) is a potential issue.
“Growers have to be open to gathering information, finding the right resources and working with educators,” said Bolt. “Go into it knowing it’s new and there will be risks and potential failures, but you can move forward.”
by Sally Colby