Kathryn Fontenot, Holzapfel, Alessandro, Kirk-Ballard, Heather
Hemp flowers produce oils containing medicinal benefits. LSU AgCenter photo by Kaylee Deynzer
Hemp (Cannabis sativa) is a versatile plant that can be grown for fiber, seed, oil and medicine. Hemp is defined as having low levels of the psychoactive component delta-9-tetrahydrocannabinol (THC) and high levels of other cannabinoids which are non-psychoactive compounds commonly used for therapeutic purposes. The 2014 Farm Act gave an opportunity for research entities to cultivate hemp to examine regional-specific best management practices before commercial hemp production was legalized.
The Agriculture Improvement Act of 2018 went several steps further and directed the U.S. Department of Agriculture to establish a national regulatory framework for hemp production in the United States. This authorized the production of hemp as an agricultural commodity for seed, fiber, grain and essential oils. The act also removed hemp from the Drug Enforcement Administration’s list of controlled substances.
In 2019, the Industrial Hemp Law was signed by Governor John Bel Edwards, which recognized industrial hemp as an agricultural commodity in Louisiana. In February of 2020, the Louisiana Department of Agriculture and Forestry began the hemp licensing application process, making 2020 Louisiana’s first year of hemp cultivation. Now that hemp is legal, the need for research is imperative for a successful local hemp industry, especially when growing in an environment which can present many challenges.
Hemp has multiple end uses, and certain cultivars are selected for specific products. Cultivars developed for cannabidiol (CBD) oil produce shorter, stockier plants and would not yield a desirable crop for fiber-end products, while fiber-type hemp plants produce tall, thin plants that produce extremely low concentrations of CBD.
This publication is focused on production of cannabidiol oil hemp plants rather than hemp plants grown for fiber.
Growers and producers must consider if there is a market for their hemp products and if a profit can be made. Fortunately, CBD oil is in high demand nationally as well as internationally. However, potential producers should be aware of some nuances associated with selling this crop.
Other challenges are the considerable legal restrictions and regulations associated with farming hemp. Farmers risk their entire crop if it goes “hot” and tests over the legal limit for THC. In Louisiana, multiple agencies regulate different parts of the hemp industry, which can cause confusion and discourage farmers from growing the crop.
The 2018 Farm Bill mandates that producers cannot grow hemp without a license and must not produce a crop that exceeds 0.3% THC content. Failure to meet these protocols would be considered a violation of the law. License applications can be acquired through LDAF at https://form.jotform.com/213404159284050.
Hemp can be a challenging crop to produce in Louisiana. This next section will address production practices hemp growers should consider when planting their first crop.
Please note, field studies were conducted in Louisiana in 2020 and 2021 in April, May, June and July with limited success. The main factors that negated heavy yields included excessive rainfall, poorly drained soil, high disease incidence and strong winds from tropical storms and hurricanes. More research is needed to make recommendations for the best management practices of hemp. However, the advice here will help you avoid some stumbling blocks that occurred in LSU AgCenter early trials.
Hemp is an annual crop mainly cultivated in temperate regions. As hemp can be sensitive to frost and freezes, initial field, high tunnel and greenhouse studies were conducted by LSU graduate students in the 2020 and 2021 warm seasons. Anderson et al., (2019) indicates optimum daytime growing temperatures are between 77 F and 82 F. To date, researchers have not found an ideal time to plant hemp outdoors in Louisiana. While field studies with different planting dates in hot spring and summer months (April through July) did not yield the best crop, greenhouse studies conducted in more temperate months (January through May and September through January) were more successful, as the environmental factors were mostly controlled in this setting.
Hemp seeds for high CBD varieties can be expensive, so determining the optimum germination conditions is critical. Optimum seed germination temperatures range greatly and are very dependent on hemp cultivars. However, Byrd (2019) found optimal soil temperatures for germination to be 59-68 F while higher temperatures (104 F) cause germination percentage to decline. In LSU AgCenter trials, seeds were started in the greenhouse with temperatures between 70 F and 83 F. Seeds were planted 6 millimeters deep in loose potting soil mixes into 4-inch “cow pots,” which are cow dung composted containers. Germination generally occurred three to seven days after seeding. Seeds were watered from 6 a.m. to 6 p.m., every two hours using mist nozzles at 30-second intervals, emitting 525 milliliters of water at each watering. Germination rate varied depending on the variety, but average success ranged from 80-95%. Due to hemp’s quick growth rate, it is not recommended to start seeds in smaller-sized containers. Fertilization of the seedlings did not occur until they had developed their first true leaf. Seedlings were fertilized after the first true leaf development using recommended rates of fish emulsion fertilizer twice a week (until transplanting in the field). Fish emulsion was used due to its relatively low levels of nitrogen to avoid burning newly sprouted plants.
Hemp is best suited to field soils with a pH between 6.0 and 7.0. Make sure your soil is loose with excellent drainage. To adjust pH, simply add lime to increase pH or sulfur to lower pH. Always make soil amendments based on soil testing. The Soil Testing and Plant Analysis Lab on LSU’s campus can provide the pH and available nutrients for both hobby and commercial producers. Hemp grows best in soils that have good drainage. Clay soils and wet soils with poor drainage will negatively affect hemp growth. Make sure your soil is loose with excellent drainage.
Preliminary trials are being conducted at the LSU AgCenter on preferred potting soils for growing hemp to flower in larger containers. Many hemp growers use FoxFarm Ocean Forest Potting soil. In LSU studies, Garden Greaux, which is formulated by LSU and currently on the market for use by home and commercial growers, is also being trialed. First year data indicates the Garden Greaux mix provides quicker, earlier growth, but as plants reach harvest, size and yields are comparable between both mixes.
Field-Grown Hemp Fertility
The LSU AgCenter field trials were conducted in the 2020 season using organic fertilizer sources. The pre-plant fertilizer was Nature Safe feather meal (13-0-0) at a rate of 100 pounds nitrogen per acre. In the LSU trials, organic pre-plant fertilizer should have been applied earlier because organic sources of fertilizer are not always immediately available for uptake by plants. If organic sources of fertilizer are used for pre-plant application, do so several months prior to planting to allow for the fertilizer to become available to plants. Plants in the initial LSU field trials looked a bit pale until fertigation applications of fish emulsion (5-1-1) and Westbrook Organics (14-0-0) water-soluble OMRI-listed (Organic Materials Review Institute) fertilizers via drip irrigation. More research is needed to optimize field grown fertility requirements in Louisiana.
Container-Grown Hemp Fertility
Preliminary container-grown hemp research at the LSU AgCenter indicates that daily fertilizer regimens should be implemented when growing hemp in containers. Daily fertigated plants grew taller and produced larger canopies with larger stem diameters than container-grown plants that were fertigated weekly. Additionally, weekly fertigated plants exhibited various nutrient deficiency symptoms, including chlorosis and purpling of leaves. This indicates that hemp is a heavy nitrogen and phosphorus feeder and should be supplied with more nutrients than traditional vegetable crops.
Cannabis plants fertilized on a daily regime, left, had much darker foliage than cannabis plants, right, that were fertilized once a week. LSU AgCenter photos by Samuel des Bordes
Greenhouse production of hemp in the 2020 and 2021 seasons was successful from seed to harvest. However, many of the varieties trialed at the LSU AgCenter were high in THC content. Flowers were harvested when the trichomes had an amber appearance, thus an earlier indication needs to be used to remain in compliance. Fertilizer used in the 2020 and 2021 greenhouse trials began with applications of fish emulsion (5-1-1) twice a week to seedlings beginning from the appearance of the first true leaf to transplanting into 5-gallon containers, approximately four weeks after seeding. The 5-gallon containers were filled with Miracle-Gro potting soil and fertilized weekly with Jack’s Nutrients fertilizer (15-0-0) at a rate of 1 tablespoon of fertilizer per gallon of water. Each plant received 5 ounces of solution.
LSU AgCenter research to date suggests cannabis plants grown in climate-controlled conditions reach maturity with less disease, insect and environmental damage compared to cannabis grown in field conditions. LSU AgCenter photo by Kaylee Deynzer
Plants absorb the majority of water and nutrients through their roots. As hemp is susceptible to disease, irrigating at the base of this crop is recommended to reduce spreading bacteria, fungi, yeasts and mold across the plant’s surface. There are many methods of irrigation depending on the size of the plots and if hemp is produced in the field or in containers.
In the LSU AgCenter field trials, hemp was planted with drip irrigation placed 2 inches beneath the soil slightly off center of each row, as seedlings were planted in a single line down the center of each row. The drip tape had emitters every 12 inches. As the crop grew, irrigation was increased to support the larger plants. In weeks with heavy rainfall, the irrigation was turned off. In fact, in the 2021 season, irrigation was rarely on because of the excessive rainfall. Producers typically plant into moist soils and maintain field moisture with drip irrigation. If the soil is particularly dry, water in each transplant on the day of planting, and then use the drip lines to maintain that moisture.
Maintaining moist soil is critical to optimum plant growth. Soil should never dry out but also not be saturated. Watering at the base of the plant helps minimize disease incidence. Irrigation time depends on soil type, size of container, nozzle type and air temperature. Check irrigation at least three times a week to determine optimum irrigation times. Water requirements increase as the plants grow larger. LSU AgCenter photo by Alessandro Holzapfel
There are many factors to consider when irrigating cannabis in large containers. Selecting the proper irrigation system is integral in producing healthy plants. Drip irrigation systems allow for container irrigation without wetting the foliage, which will help prevent disease. Drip emitters can be connected to “spaghetti tube” that circles the plants stem, allowing for delivery of water around the circumference of the container. This configuration will allow for uniform watering of the container and prevent dry and hydrophobic sections within the growing media. The amount of water delivered to each container will depend on the size of the plants, the weather and the media used. In general, irrigating 10-20% of the container volume daily is sufficient, but this should be monitored regularly to ensure uniform wetness within the media.
In LSU greenhouse trials, hemp seedlings were transplanted into 5-gallon containers and fitted with irrigation including spaghetti tubing emitters. Irrigation was applied six times a day for three-minute intervals (releasing 48 milliliters of water at each irrigation event), with one hour and 30 minutes between each application. After two weeks, irrigation was increased to four-minute intervals (releasing 65 milliliters of water at each irrigation event) to accommodate for increased plant biomass. The goal is to maintain soil moisture in the container without excess leachate running out of the bottoms of containers to avoid nutrient loss.
Hemp can be categorized in two ways with respect to light response: day-length-sensitive (photoperiod sensitive) and day-length-neutral (auto-flowering).
Insects can damage the leaves, stems and flowers of hemp plants and subsequently reduce the yield and quality of the product. Scouting should occur daily, especially in the nooks of the flowers and in places where insects can hide on the plant. At this time, there are limited products that are labeled for insect control in a hemp crop. The insects most commonly seen in the LSU AgCenter hemp trials were fire ants, yellow-striped armyworms and corn earworms. Please note, many more insects can affect hemp growth.
In the 2020 and 2021 field and high tunnel hemp experiments, a number of diseases were recorded. The most commonly occurring diseases included southern blight (Sclerotium rolfsii), stem canker (Botryodiplodia sp.) and root rot (Phytophthora root rot). Limited fungicides are labeled for use in hemp fields. Using common best management practices for crops, one can reduce disease incidence in hemp.
Common best management practices to avoid disease include:
To see approved pesticides for use on hemp, visit https://www.epa.gov/pesticide-registration/pesticide-products-registered-use-hemp.
Where you choose to grow your hemp crop can present varying degrees of challenges from high to low startup costs and even the overall ease of production and harvest. Location may even affect the quality of flowers that are harvested because of presence or lack of environmental challenges. Table 2 displays a ranking of lowest (1) to greatest (5) challenges in production from outdoor to indoor locations.
A postharvest facility is crucial for successfully completing the hemp production process. Hemp requires an environmentally controlled area for drying, trimming and storing the product until sale and distribution. Even though the product has been removed from the field, post-harvest diseases such as gray mold can occur rapidly. Optimum drying and storage conditions are 70-75 F with a 35% relative humidity. Adequate space between plants when drying is also important. All flower material must be dried to a moisture content below 12% as per 2018 USDA Farm Bill protocol.
An important factor to consider is extraction and processing delays. With the rise in hemp production, there has been an influx of new producers with a shortage of extraction and processing facilities. Industrial hemp producers should be prepared to store their product for up to one and a half years for processing. Once the product is returned to the original producer, it can be marketed for sale to retailers or wholesalers. These delays can affect the timing of the return on your investment, so planning for unforeseen waiting periods is imperative.
When dealing with a semi-perishable crop, it is always a good idea to have contracts with buyers prior to growing the crop. This may require growing a small subset of the greenhouse or field to provide samples to buyers to show them the quality and conditions of the product that you’re able to grow. Then, you can begin full production the following year once you have contracts in place.
Postharvest conditions of hemp are critical. Store hemp plants where they can remain dry and at a constant temperature of 70 to 75 F with a relative humidity of 35%. If possible, have space between plants so air can naturally flow through the storage area to avoid mold. LSU AgCenter photo by Kaylee Deynzer
Many farmers, despite the crops they grow, face the same issues — weather, salary, crop loans and more. Below are a few items to note when developing a budget for growing hemp.
It is difficult to predict the economic viability of industrial hemp in the United States due to a lack of historical data. This is especially true when trying to predict the sustainability and capability of the hemp industry in Louisiana in the long term. However, in the short term, the hemp industry has come a long way from 2018 to 2022. These are all indicators for a stable and robust industry, however, only time will tell if this trend continues. It should be noted that outside factors, such as the approval of recreational marijuana, could potentially impact the viability of hemp.
When considering hemp farming, weigh your options carefully with the knowledge that certain factors, although risky, are on your side.
There is still work to be done when it comes to the industry’s infrastructure. Many relationships must first be established, and many structures built, however, one may also consider that it is easier stepping into an empty room rather than a full one. Another cause for concern is Louisiana’s above-average risk of devastating storms that pose a threat to the financial wellbeing of the owner and their operation. While Louisiana suffers from hurricanes, states in the Midwest face tornadoes, and other parts of the country experience excessive droughts and floods.
More research needs to be conducted in Louisiana to create budgets and profit trends for this crop. Even with the pitfalls encountered since Louisiana’s first crop in 2019, there is still a potentially bright future for hemp in Louisiana. Farmers can consider hemp a semi-safe bet, however, even the safest bet is still a gamble at the end of the day.
For tables on cultural and pest-related challenges of growing hemp, as well as location challenges, please see PDF.