Hemp Plant Sex Identification

Save time and resources by eliminating male plants early in the grow cycle! Early plant sex testing allows you to focus on only the female plants, resulting in a more robust crop with increased yield.

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While most plants contain both male and female sex organs, hemp plants are dioecious, meaning that each plant is either male or female. This is important in the cultivation of hemp because male and female plants have very different characteristics. When properly cultivated, the female plants develop large trichome-rich buds containing cannabinoids and terpenes. Male plants, however, develop pollen sacs but do not grow buds. If left in a grow, male plants will pollinate the females, leading to smaller, seed-containing buds and lower yield. Therefore, it is desirable for a crop to contain only female hemp plants.

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Male and female plants appear identical for up to 6 weeks after germination, when phenotypic changes begin to appear. Even then, visual identification is difficult, and errors can lead to a greatly inferior crop if any male plants are overlooked. In addition, precious resources are wasted on weeks of cultivation of males before they can be identified and removed.

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By identifying and removing males shortly after germination, females can be cultivated to grow more robust in size and cannabinoid content. We utilize  a Quantitative Polymerase Chain Reaction (qPCR) assay to identify a gene specific to male plants. Using qPCR, we can distinguish male plants on a molecular level as soon as 1-2 weeks after germination with a high degree of accuracy. This allows for their removal very early in the grow cycle, and virtually eliminates the possibility that an errant male plant will disrupt the optimal development of buds produced by the females.

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While most growers prefer to eliminate male plants, early identification of plant sex is also valuable to those involved in hemp breeding projects. Male plants may be isolated and allowed to further develop. Strong male plants can then be selected for future breeding.

Whether for breeding programs or optimization of crop yield and quality, identification of the sex of hemp plants is of utmost importance. Early, accurate determination saves time and resources, and increases the likelihood of optimal crop growth. Sex detection by qPCR can be performed as soon as the second set of true leaves emerges, or any time thereafter. The sample size required is one small leaf from the seedling. For larger plants, a whole leaf or a lobe of the leaf may be provided.