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when to sex cannabis plants

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.

How to Predetermine the Sex of Cannabis Plants

Monday October 28, 2019

F emale cannabis plants are the only ones that produce flowers. Male cannabis plants produce pollen which, if exposed to female cannabis plants, will result in seedy weed. Therefore, to cultivate seedless cannabis buds (a.k.a. “sinsemilla”), you must remove all males from a grow environment before pollen sacks form. To do so, you must determine a plant’s sex before they transition from veg to flower. Though most cloned cannabis plants will be female, cannabis grown from seed could be either/or (unless growing feminized seeds, that is). Today, we’ll explain how to determine the sex of your cannabis plants before they have a chance to either pollinate or become pollinated.

Why Sex Cannabis Plants?

As mentioned, male cannabis plants produce pollen which can easily spread throughout a grow area. In fact, a single male plant can pollinate hundreds of females within a single grow space! To make matters worse, male cannabis plants develop pollen sacks before females begin producing buds. It often takes around one to two weeks for male plants to begin producing pollen sacks (characterized by a small “sack” as opposed to a white “hair” or pistil) whereas female plants often take two to four weeks or longer to show gender.

Though genetically speaking, this is a great way for plants to ensure reproduction, modern grow techniques advise against this. After all, once a male cannabis plant drops pollen, any nearby females will produce seeds in response. This not only increases weight, but it also reduces potency and adds one extra step to the smoking process.

Steps for Sexing Your Cannabis Plants

There is an easier way to determine the sex of cannabis plants than to simply watch, wait, and hope it’s not too late. Specifically, you can “force sex” a plant to determine its gender before flowering the whole thing. To force sex a cannabis plant, simply place its clone in a 12/12 light cycle (12 hours of light/12 hours of complete darkness). This photoperiod manipulation signals to the plant that it is time to start flowering whether the plant already has roots or not.

Because clones are exact genetic copies of their parents, forcing a clone to flower separate from its parent will give you a clue regarding the specific gender of its parent.

If a clone produces pollen, you know its parent is a male. Conversely, if the clone begins to flower (look for those pistils), you know its parent is female. Now you can remove all male parents leaving only the females behind to flower. No pollen, no seeds, only happy girls and bountiful buds.

Other things to look out for which may help you determine the sex of your cannabis plant include the plant’s height (males tend to be taller than females though much of this depends on the strain type, as well) and the size of the calyx, or the center-most part of a flower. If the calyx is large with a protruding white hair, it is likely female. On the other hand, if small and swollen with no hair, it’s likely a male. This distinction can be made before the plant begins flowering during a stage called “pre-flower.” However, it can be difficult for the naked eye to determine gender at this stage; a jeweler’s magnifying glass can help, though.

Experienced cannabis growers understand the importance of separating male from female cannabis plants. With a little practice, many can catch and dispose of males long before they have the chance to pollinate females. Fortunately, even if you’re just starting the homegrown cultivation process, you can sex your plants before it’s too late, as well. Use these tips to predetermine the sex of your cannabis plants so that your girls will thrive unadulterated.

Do you have tips for determining the sex of your cannabis plants? Share them in the comments below!

Abby is a writer and founder of Cannabis Content, a marketplace designed to connect cannabis writers and creatives with businesses in the industry. She has been a professional cannabis writer since 2014 and regularly contributes to publications such as PotGuide and M&F Talent. She is also the Content Director at Fortuna Hemp, America’s leading feminized hemp seed bank. Follow Abby on Facebook, Twitter, and Linkedin.

Knowing if a cannabis plant is male or female is an important aspect of marijuana cultivation. Find out how to tell the sex of a cannabis plant in early stages, as well as the benefits of sexing your cannabis plants as soon as possible. ]]>