Harvesting hemp grains for seeds is ready to be collected 105-115 days after sowing. Farmers can expect a yield of around 1,000 pounds per acre, according to Greg Luce, University of Missouri Extension agronomist. Traditional harvester equipment can be used for this purpose. Growers must harvest hemp for grain as soon as the seeds start to break.
Hemp for fiber must be harvested after the plants flower and before the seeds set, says Pear. A non-autoflowering strain takes 100 to 120 days to reach the maturity necessary for the harvest. Water, sunlight and nutrients are the most important factors for hemp growth. Hemp is usually sown after spring wheat or barley, but before sweet corn in a growing region.
Autoflowering varieties have a limited range from sowing to harvest, from 50 to 80 days. Varieties of hemp with essential oil and hemp fiber require 70 to 120 days from sowing to harvest, and hemp grain requires 120 to 180 days. Soil temperature, the length of the growing season and the danger of frost determine when to plant. Some hemp varieties germinate at temperatures as low as 35° F, but germination is faster and more reliable when the soil is around 50° F.Sowing too early can expose seedlings to frost damage.
Young hemp seedlings and mature plants can survive light frosts, but early fall frosts can trigger the drying process that stops growth and leads to early seed formation. When harvesting cannabinoids, check trichomes regularly; a change in their color from white to a milkier, whitish color is a sign that it's time to harvest. Whether growers harvest hemp by hand or mechanize the entire process, planning ahead and gathering the necessary labor and equipment is essential. Seasonal staff have a half-day orientation and ongoing on-the-job training to ensure that hemp is harvested, dried and stored properly. The cost of a harvester could be out of reach for most small hemp growers, but Mahan believes producers can place cheap sickle rods or hay rakes on their tractors to increase efficiency and reduce labor costs at harvest time. It's easier to harvest hemp before the humid fall weather arrives because moisture increases the risk of mold or mildew ruining the crop.
Thanks to the rapid growth of the hemp industry, Ellison points out that a growing number of companies have begun to develop machines that can help with the harvest. Although not recommended, the denser population of hemp with essential oil would have a row orientation separated by 3 feet with plants spaced every 3 feet within a row, resulting in a final density of approximately 5,000 plants per acre. Mechanization can be a challenge because the burgeoning industry lacks sufficient specific harvesting equipment for hemp, forcing many producers to equip machines to help with the process. Severe storms can also delay the harvest, affecting the quality of the grain or fiber of hemp or causing the harvest to heat up. In this two-part series, growers and researchers share tips, methods and best practices for harvesting hemp for fiber, grains and CBD. Ellison believes that labor is one of the biggest problems for those who grow hemp for CBD and other cannabinoids: “The harvest is absolutely the highlight”.
Starting small also allowed Barry, with the help of agronomist and hemp specialist Kelsey VanOverbeke, to pay close attention to the intricate details between sowing and harvesting that might have been overlooked.