Answers to Common Cannabis/Hemp Gender Questions

Cannabis and hemp are dioecious plants, meaning they either male or female. If your goal is to grow cannabis or hemp for cannabinoids, terpenoids, and flavanoids, then you only want to grow female plants. 

How do male cannabis/hemp plants ruin a grow? 

Male hemp and cannabis plants produce pollen, which fertilizes female plants and causes them to produce seeds. For industrial hemp growers producing grain or fiber, this is not a problem. Industrial hemp is often harvested for its nutritious seeds or fibrous stalk, not its cannabinoid and terpene-rich flower.

However, seeded flower is the last thing a farmer wants when their goal is to produce cannabinoids, terpenoids, and flavanoids. When males pollinate a hemp crop, that crop loses 50% of its biomass and 30% of its total cannabinoid content. This is because females spend energy that would have been spent producing big, resinous flowers towards producing seeds.

What percentage of traditional cannabis/hemp seeds are male?

The natural female/male ratio in traditional cannabis and hemp seeds is approximately 65:35. Cannabis spreads its pollen through the air, without the need for pollinating insects, and therefore fewer males are needed to do the job.

When do cannabis/hemp plants show visual signs of sex?

Cannabis and hemp plants show visual signs of their sex after about 6-8 weeks of development. These are known as “pre-flowers.” Male plants will start to develop pollen sacs between their nodes to spread pollen, while female plants will develop stigma between their nodes to catch the pollen. 

Although this is the simplest method for identifying plant sex, it is labor-intensive and comes at a cost. Cultivators have to invest 6-8 weeks of resources into plants before scrapping 35% of their crop. This also means they only end up using 65% of their total canopy. 

How early can cannabis/hemp plants be genetically tested for sex? 

We recommend cultivators wait until seedlings develop the second set of true leaves before testing with our FemINDICAtor qPCR Plant Gender Assay. DNA is extracted from one of the plant’s leaflets using a simple boil prep, and then run on a qPCR machine with the FemINDICAtor assay to determine the plant’s sex. Instrument run time is just 2 hours.

What are feminized cannabis/hemp seeds and how are they made?

Seed producers offer feminized seeds, which should only produce female plants. They do this by basically forcing a female plant to produce viable pollen by applying certain chemicals. That pollen is then applied to other female plants so that only female sex chromosomes are being shared. When this is done properly and in a controlled environment the resulting seeds are properly “feminized”.

Can genetic testing identify hermaphrodites? 

No. Cannabis plants typically hermie as a response to stress. Although there may be genetic markers that determine if a plant is more likely to hermie, we have not found them, and we do not target them with our gender test. The FemINDICAtor Gender Assay specifically looks for a Y chromosome.

How can I get started with genetic sex testing?

There are labs that offer genetic testing as a service, but cultivators can test their own plants in-house using the FemINDICAtor® qPCR Gender Detection Assay. Get started today with our FemINDICAtor and Chai Open PCR Starter Bundle and you will get all the reagents you need to test your first 200 plants, plus a two-channel qPCR instrument to run them on.