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how to sex cannabis plants

How to sex cannabis plants

On the flip side, the following factors may possibly increase the ratio of female plants with regular seeds (learn more):

Once a cannabis plant is about 3 weeks old, its sex is pretty much completely set and can be determined either by visual inspection or by chemical leaf test.
If you click the following picture and zoom in close, you can see pollen sacs scattered among the leaves

Although testing can be done as early as week 1 from germination, waiting until week 3 to conduct testing on seedlings can increase accuracy, and some companies won’t conduct testing until week 3.
Knowing the plant’s sex is helpful because most hobbyist cannabis growers would like to identify and remove male plants from the grow room early in the growing process. This is because only female plants make potent buds/flowers, while male cannabis plants make non-potent pollen sacs where female plants would grow buds. Additionally, female buds need to avoid pollen from male plants in order to make the highest quality cannabis (sinsemilla or “no seeds”).
When I first started growing weed, I learned (incorrectly) that there is no way to determine a cannabis plant’s sex until the flowering stage. But I’ve since learned that pre-flowers can reveal the plant’s sex while it’s still in the vegetative stage! Cannabis plants grow pre-flowers as young as 3-4 weeks from germination for male plants, and 4-6 weeks from germination for female plants.
In general, the tests are available for seedlings as young as 1-3 weeks. Sex testing uses a real-time polymerase chain reaction (qPCR) test, and potency tests use Gas Chromatography with a Flame Ionization Detector (GC/FID) or High-Pressure Liquid Chromatography with a Diode Array Detector (HPLC) for testing.
Male pre-flowers tend to be shaped somewhat like a spade

Although these are the general shapes of male and female pre-flowers, if you continue looking through the pictures below, you’ll see there’s quite a bit of variation on what pre-flowers look like from strain to strain.

Learn how to find tiny pre-flowers at the base of each leaf to determine the sex of your plant in the vegetative stage (at only 3-6 weeks from germination)!

How to sex cannabis plants

There are two types of hermaphrodite plants:

Pre-flowers begin to develop four weeks into growth, but they may take a little longer depending on how quickly the sprouting phase occurs. By the sixth week, you should be able to find the pre-flowers and confidently determine the sex of your plant.
Sexing cannabis plants is easy. Let’s see how to tell.

Though there are other methods to determine what sex the plant is, examining pre-flower formation is the most reliable.
Seeded buds are generally regarded as low-quality cannabis. When seeds are present, the smoke is harsh and unpleasant.
This post was originally published on September 19, 2017. It was most recently updated on February 11, 2020.
If you’re interested in pollinating portions of your crop, remember that pollen is extremely potent and very good at traveling. Keep your males intended for pollination far from your garden space and work carefully with that pollen.
With cannabis, females are usually isolated away from males—introducing males into a garden will result in pollination, causing females to create seeds.

When a female plant develops both male and female sex organs, it is considered a hermaphrodite. This means your cannabis plant is now capable of producing pollen that can pollinate your entire garden. “Herming out,” as some call it, is something that generally happens when a plant becomes excessively stressed. Some plant stressors include:

Determining the sex of your cannabis plant is vital to achieving your growing goals. Luckily, sexing cannabis plants is easier than one might think.