Source: NCSU COOPERATIVE EXTENSION, 5/10/21


Introduction
When growing hemp for extraction of cannabinoids it is critical that only female plants are produced. Female flowers (“buds”) are densely covered in cannabinoid-rich trichomes as compared to male flowers, which produce very little in terms of cannabinoids. What males do produce is an abundance of pollen, which can threaten the yield and quality of a floral hemp crop. Female plants that are pollinated show a decrease in floral yield and cannabinoid concentration compared to non-pollinated plants. Meir and Mediavllia (1998) showed that unpollinated females produce up to 2-5x more extractable oils compared to pollinated plants.

When hemp was first legalized, growers utilized asexually propagated transplants (“clones”) to ensure that only female plants were produced. Since then, we have seen a shift towards the use of feminized seed. Compared to clones, feminized seeds are more economical and give the farmer more control over transplant production if they are unable to produce clones. But what happens if your neighbor is growing grain or fiber hemp, which has a mix of males and females? Hemp pollen is wind-dispersed and has been shown to travel at least 3 miles (Small and Antle, 2003). Unfortunately, this has already led to a number of lawsuits among neighboring farmers whose all-female floral hemp crop was pollinated by a neighboring grain/fiber crop (“Oregon industrial hemp litigation”, 2018).

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