Sexing cannabis plants is a crucial step for a successful harvest. Many new growers feel nervous about determining the sex, as experience does count. However, knowing exactly what to look for, setting the correct light schedule and giving plenty of attention is all it takes. A magnifying glass will come in handy, as the sex organs are super tiny.
Why is sexing cannabis plants important?
A cannabis plant typically produces either male (pollen-producing) or female (seed-producing) flowers. Cannabis grown with the intent of harvesting THC-rich buds requires non-pollinated female plants. In that case, keeping the sexes separate is vital. It takes just one male plant to fertilise a whole room of females, so act quickly.
How to see if your cannabis plant is male or female
Around 6 weeks after germination (outdoors), or 1 week after initiating the flowering stage (indoors), the tiny buds (sex organs) begin to develop at the nodes of your plant. The male plants will develop pollen sacs that resemble a bundle of balls. These can appear a week or two before female flowers, and won’t grow hairs. At this point, you can start trying to distinguish the sex of your cannabis plant:
- Look 3-5 nodes up the stem (about halfway up).
- Study the tiny buds growing at the nodes.
- Female: look for 2 thin hairs (stigmas), growing out of a slightly open tear-dropped bulb (bract).
- Male: look for 2-3 pollen sacs, resembling balls and surrounded by flowers (males will not grow stigmas).
Female cannabis plant
Male cannabis plant
As time passes, visible changes to your plant will be observed, though some strains can take longer to develop than others. If you’re unsure when sexing your cannabis plant – take a step back and wait one more week. By 8 – 10 weeks after germination (outdoors) the flowering stage should be well underway and sex should be obvious.
Now and again, plants will present with both male and female flowers and are known as hermaphrodites. This can occur for two reasons: genetic predisposition or environmental stress to the plant during the flowering stage. It’s most likely to happen towards the end of the flowering period, so do keep a close eye on your plants. Like males, you’ll want to keep hermaphrodites separate from your female plants, to prevent pollination.
You can lower the risk of hermaphroditism occurring by choosing a feminized autoflowering strain.
When to induce flowering, and when to sex cannabis plants
At around 6 – 8 weeks old, cannabis is ready to transition into the flowering stage. Flowering is induced when the light schedule follows 12 hours of sunlight and 12 hours of (uninterrupted) darkness. Indoor and outdoor plants follow the same basic light schedule, unless they are autoflowering.
Pre-flowering buds can be observed under a magnifying glass within the first ten days of adjusting the light schedule. At this stage experienced growers may begin to detect plant sex, but don’t worry if you’re not sure, just wait a little longer.
Flowering cannabis while growing outside
Towards the end of summer, the hours of sunlight in a day begin to decrease, and the amount of darkness your plant is exposed to will increase. Wait until the hours of light per day reach 12 hours and ensure plants receive 12 hours in complete darkness. About 10 days after this point (usually the summer solstice in the northern hemisphere) you can start to check as above.
The choice of cannabis strain will vary depending on the climate, and the months of flowering are determined by whether you are growing in the northern or the southern hemisphere.
If you are in Northern or Eastern Europe, you are in the cool-temperate zones. This means your cultivation season typically begins late April to early May and through to the end of September. Northern summers are short and mild with usually only a single outdoor harvest per year. Indica strains tend to grow well in cooler climates.
Southern and Western Europe are in warm-temperate zones. Southern summers are typically long and sunny, and the good weather can last until late October. Ideal circumstances to cultivate late-flowering varieties like sativas.
Keeping a close watch can help you figure out what stage of flowering you are in. Before true flowering begins, there is a stage known as pre-flowering, and this is when the plants will start to display male or female characteristics. Outdoors, pre-flowering usually begins about six weeks after germination.
If you can see the 2 white ‘hairs’ (the stigmas) growing at the plant’s nodes, but no buds have developed yet, you can safely assume that the plant is female and you are about to begin the flowering stage. If you can’t see any hairs, wait another couple of weeks and keep checking every couple of days to see if they are developing, or if balls are starting to develop instead.
Flowering cannabis for growing indoors
It won’t matter where in the world you are – when growing indoors, simply adjust the timer on your lights to follow the 12/12 light schedule. This is the beauty of growing indoors, because you can easily track what stage of flowering you are in and manipulate the plant growth cycle to induce flowering.
Can I avoid sexing cannabis plants?
Sexing cannabis plants will only be necessary if you’ve purchased our regular seeds such as Skunk #1, Jack Herer, and Master Kush. Those seeds will turn out to be roughly 50:50 male/female plants (on average) and are great for testing and developing your cannabis sexing skills.
Avoid sexing altogether by sticking to our feminized seeds like Northern Lights Feminized, Hindu Kush Feminized, and Afghani #1 Feminized. All our autoflowering seeds are feminized, and our cannabis strains range from having a short flowering period to strains with a relatively long flowering period, depending on your grow goals.
It may take some time before you feel totally confident sexing your plants, so don’t be afraid to experiment. Remember to stay patient and observant over the next 3-4 weeks. Keep a strict 12/12 light schedule and avoid stressing out your plant. If you still have questions, or have any tips for germinating cannabis seeds, please share them in the comments below.
- Disclaimer:Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.