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Hemp: A new crop for you?

Horticulture has seen many trends over the decades, some small and some large. As states come on board with programs allowing cannabis production, the impact to horticulture is incredible, affecting growers and suppliers in many ways. Many traditional horticultural growers see these changes and welcome the opportunity to be a part of this new arena. The question is, "What is the best way for my business to be involved?”

by Tami Van Gaal

Two primary segments of the cannabis arena, medicinal and recreational marijuana crops, receive a great deal of attention from both mainstream and industry media. Thirty states currently permit medicinal and/or recreational marijuana production, and regulations vary widely by state. While some states have relatively open regulations (e.g., CA, OR, WA, CO, MI and OK), many states are more tightly regulated with limited opportunities for traditional growers to enter. Additionally, marijuana production under cover (warehouse and greenhouse) can be a costly endeavor for new builds and renovations. Fortunately for those with interest, there is another way.

Section 7606 of the Agricultural Act of 2014 (the 2014 Farm Bill) opened the door for cultivation of industrial hemp on a state-by-state basis, when grown as part of a research program associated with an institution of higher learning or state department of agriculture. Hemp is cannabis, but it’s different from marijuana. It all comes down to THC content. Cannabis sativa with greater than 0.3% THC by dry weight is defined as marijuana. C. sativa with less than 0.3% THC by dry weight is defined as hemp. Industrial hemp has a long history of use in fiber, textiles, animal feed and more. The most recent interest, however, is for production of cannabidiol (CBD). Unlike THC, CBD is not psychoactive.

CBD is extracted from the cannabis plant and offered as a supplement/treatment for medical conditions such as seizures, pain, anxiety and depression.

Hemp can provide strong potential as a diversification crop for ornamental growers with a bit of land. States with pilot programs for hemp production generally have lower barriers to entry compared to commercial marijuana production, and production needs are relatively simple. Currently, 40 states have industrial hemp programs in place. Rules vary by state, and growers must be registered/licensed to grow hemp. Note that CBD products are often state regulated and all forms of cannabis remain federally illegal.

Production is much simpler for hemp than for marijuana, generally following a tobacco-like model. First, while hemp liners are produced in the greenhouse, most hemp production occurs in an agricultural field under natural light. Second, while hemp is a short-day plant (like a mum or poinsettia), the liners are produced in late spring, so there is minimal need for supplemental lighting to keep the plants vegetative. Finally, there’s nothing mysterious about hemp production – the liners are grown in conventional trays with conventional media and with conventional fertilizers.

For key production considerations, let’s start in the field. Hemp for CBD is grown differently than hemp grown for fiber. Fiber crops are grown like grain crops in open fields and are bulk harvested. Hemp grown for CBD extraction is generally grown in spaced rows. Also, when growing hemp for CBD, the focus is on female plants. Males bring the risk of fertilization, which can result in high THC levels and lower quality CBD oil. This is different from industrial production for fiber, which utilizes both female and male plants. Therefore, anything that can be done to increase the percentage of female plants being planted will greatly reduce labor required later to rogue males.

Reducing the presence of males starts in propagation. If growing from seed, start with feminized seeds, but recognize that this doesn’t guarantee only female plants. Plan to scout phenotype and rogue starting around week six. Alternatively, grow from cuttings from mother stock (female stock plants). DNA-based testing is available for sexing and is financially practical for stock plant production, but probably not for the thousands of plants that go to the field. The stock plants (aka “the moms”) must be grown under long days to maintain vegetative growth. Long days can be achieved with HPS or LED lights with day extension or with other night interruption methods.

Speaking of lights, use of lights and light deprivation systems is common practice when growing marijuana year-round. However, with a target field transplant date of May 15-June 15 for most areas (avoid planting to the field after July 1), the liner crop won’t need supplemental light because the day length is adequate over the two to three weeks of production time.

The two- to three-week crop time can easily fit into your greenhouse once you start selling your first round of spring crops. Start with soft cuttings. It’s common for cannabis growers to take 4-6 node cuttings, but smaller cuttings should be successful. Stems are generally cut at a 45° angle, with cuttings quickly submersed in water to protect the hollow stem. Rooting is best achieved with the use of rooting hormone and bottom heat. Maintain long days (16 hours, natural or artificial) and feed sparingly at 50 ppm once rooting occurs. Maintain media pH at 5.8-6.2 in the media of your choice (peat-based, coir-based or inert media all work well). Pinch prior to transplant and take care to avoid root-bound liners. Also, avoid drought stress, as this will stunt plants.

Hemp has a few specific needs in the field. It’s sensitive to waterlogged soils; consider using raised beds and plastic row cover to minimize this risk. Avoid drought stress, as this can lead to development of male flowers. The best way to manage the crop is with drip irrigation, which can be supported with an injector to make nutrient supply more efficient. Alternatively, consider use of slow-release or controlled-release fertilizers.

Planting densities range from 600 to 800 plants per acre to 2,000 plants per acre. Wider spacing will allow space for larger plants. Speaking of the field, recognize that planting next to agricultural crops will very likely increase the risk of insect pests migrating to your hemp crop.

If you’re interested in producing hemp for CBD, fiber or other use, check with your state regulating agency to understand the registration/licensure process. Your extension agent should be able to direct you to the proper office or you can search “industrial hemp” with your state name to find information online. It would also be a good idea to check with an attorney well-versed in hemp production in your state. Since cannabis is still illegal at the federal level, most organizations run their hemp operations separate from their traditional greenhouse operations, i.e., separate businesses. Finally, join your local hemp growers association for mentoring support and collective influence with regulating agencies.

Once you’ve done your research and decided to grow hemp, remember to reach out to your supplier partner. We’re working with hemp growers across a number of states, and can supply you with the products and knowledge to grow a successful crop.

Tami Van Gaal is the CEA division leader for Griffin. She can be reached at

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