Evaluating Chinese fiber hemp (Cannabis sativa L.) varieties and planting dates in North Carolina

Field trials were conducted in 2021 and 2022 to evaluate the effects of planting date (mid-March, mid-April, and mid-May) on 11 fiber hemp (Cannabis sativa L. <0.3% total tetrahydrocannabinol) varieties. Trials were conducted in Goldsboro, Kinston, and Salisbury, NC. Each location followed a split-plot randomized complete block design with at least three blocks where planting date was the main-plot and variety the sub-plot. Varieties investigated originated from China and Australia (2021 only). Data collection included flowering time, end of season stand counts, stem height, diameter, and final retted dry straw yield. We found differences among the varieties investigated in both years; however, no distinct trend was observed across years. All varieties investigated flowered at the end of August and beginning of September, allowing for a long growing season and ability to produce abundant biomass. In general, the Chinese genetics yielded higher stem biomass compared to previously reported European genetics. Stem thickness was >7.5 mm, which is generally considered the maximum width for textile-grade fiber production. To achieve thinner stems from the varieties investigated, harvesting prior to male-flower initiation may be required. The crop experienced temperatures below freezing in both years with no signs of damage. Taken together, farmers seeking to plant fiber hemp in North Carolina have a wide planting window from mid-March to mid-May using these Chinese varieties.