how to sex marijuana seeds

Sex Determination: After Planting Marijuana Seeds

Identifying Males and Females from Marijuana Seeds

When Growing marijuana seeds there is a chance it could be female or male, you can increase your odds for females if the growing conditions are optimal. After planting marijuana seeds and letting the plants vegetate for a while, the next step is to determine the sex of the plants also known as sexing. Determining the sex of a plant can be tricky if you don’t know what to look for. It is best to determine the sex as early as possible. Determining a plants sex protects against unwanted pollination resulting in marijuana seeds . Males have no use in the garden, unless you are planning on breeding plants. They also could be disastrous to the crop if their flowers open and pollinate the female flowers. Pollination creates marijuana seeds which lowers the potency and overall usable weight. Pollinated female flowers will spend all their energy making seeds instead of buds.

Determining Sex After Planting Regular Marijuana Seeds

There are several methods you can use to determine sex. Early growth in a plant such as height and vigorous growth can indicate a sign of a male but this is not an optimal way of sexing a plant. Discussed below are the two best ways to determine sex in young plants that you grow from regular marijuana seeds.

The first way to determine sex is early visible detection. In some strains but not all of them, there is a single small female or male flower that shows in vegetation. The flower can be located by looking at the nodes of the plant where the leaf petioles and the stem meet. The plant is the same sex as the little flower showing. Normally my plants in vegetation start showing sex after they are about 30 centimeters tall.

The small female flower is called a calyx.

The small male flower looks like a ball it is a pollen sac:

When the above method does not show a small flower there is a different way to determine sex and that is to induce early flowering. Light cycle manipulation, is forcing a plant to flower and show its sex. This can take up to ten days to do. It also takes ten days to switch back to vegetative growth. Instead of forcing the whole plant to flower a simpler way is to take cutting of the plants you want to determine sex.

Label the clone and the mother plant so you know what cutting came from the matching mother plant. Place cutting in a cup of water or in a planting mix under a flowering light schedule of 12 hours on and 12 hours off for at least 10 days. Giving the cutting more darkness speeds signs of flowering by a few days such as 8 hours of light and 16 hours of darkness. Within 10 days the cutting will show flower signs and indication of sex is visible. Once you have determined the gender of the cuttings, you should get rid of any males. So remember if you grow marijuana seeds you have to determine sex of the plants so males don’t pollinate your females. Choosing marijuana seeds can be difficult, but if you would like to avoid checking for sex make sure you get feminized cannabis seeds.

When Growing marijuana seeds there is a chance it could be female or male, you can increase your odds for females if the growing conditions are optimal. After

Male vs. female cannabis: How to determine the sex of your plant

In the world of plants, reproduction can happen in a variety of ways. Monoecious plants produce two different types of flowers on the same plant, and hermaphrodite plants grow single flowers that have both male and female reproductive organs.

Cannabis is a dioecious plant, meaning male or female reproductive organs appear on different plants.

With cannabis, females are usually isolated away from males—introducing males into a garden will result in pollination, causing females to create seeds.

This is important for a breeder to achieve new genetics, but most growers remove the males to allow females to produce seedless buds, also called sinsemilla. These are the resinous buds that appear on the store shelf; they all come from female plants.

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Seeded buds are generally regarded as low-quality cannabis. When seeds are present, the smoke is harsh and unpleasant.

Female genetics can be guaranteed by obtaining clones and feminized seeds. If, however, you’re working with regular seeds and are unsure of your seed’s sex, knowing how to determine the sex of your plant is vital to developing new genetics, gathering seeds, or growing sinsemilla.

Sexing cannabis plants is easy. Let’s see how to tell.

Check out these additional resources for more info on cannabis seeds:

How to determine the sex of a cannabis plant

Female cannabis pre-flowers grow as tiny bracts with hair-like stigma peeking out. Male plants produce small, round balls at the nodes. (Amy Phung/Leafly)

Cannabis plants show their sex by what grows in between their nodes (where leaves and branches extend from the stalk). Pollen sacs will develop on a male plant to spread seeds and stigma will develop on a female to catch pollen. You can see these differences weeks before they actually start serving their purposes in the reproduction cycle. These are known as “pre-flowers.”

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.

Pre-flowers can initially be extremely small and hard to identify with the naked eye, but you can use a magnifying glass to get a better look. Examine the nodes of the plant and look for either the early growth of small sacs on a male, or two bracts on a female, which will eventually produce the hair-like stigma.

Though there are other methods to determine what sex the plant is, examining pre-flower formation is the most reliable.

Removing males early on is important for two reasons: it frees up space in your garden so females can grow bigger and stronger, and it prevents males from pollinating females.

What are hermaphrodite cannabis plants?

Hermaphrodite cannabis can express both sex organs and self-pollinate. (Amy Phung/Leafly)

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:

  • Plant damage
  • Bad weather
  • Disease
  • Nutrient deficiencies

There are two types of hermaphrodite plants:

  • A plant that develops both buds and pollen sacs
  • A plant that produces anthers, commonly referred to as “bananas” due to their appearance

While both result in pollen production, true hermaphrodites produce sacs that need to rupture, while anthers are exposed, pollen-producing stamen.

Because this occurs when cannabis is under stress, it’s important to monitor plants after they have been exposed to stressors—indoors: high temperatures or light leaks are often the cause; outdoors: a snapped branch might be repaired and then turn into a hermaphrodite.

The other primary cause of hermaphrodite plants lies in the plant’s genetics. A plant with poor genetics or a history of hermaphrodite development should be avoided to protect your garden. If you notice any pollen sacs or anthers at any point, remove the plant from your garden immediately to prevent pollination of female plants.

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.

This post was originally published on September 19, 2017. It was most recently updated on February 11, 2020.

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