Sexing Weed Seeds

When sexing cannabis plants, most growers separate the plants by gender as the flowering stage begins. Avoiding pollination is key for a successful harvest. If you're interested in growing cannabis, determining the sex of your plant is a critical aspect in the cultivation process. Learn whether or not you can tell if a marijuana seed is male or female and more information about feminized seeds. Male vs Female Cannabis Cannabis is a dioecious plant, which means it has male and female flowers on separate plants. When the male plant enters the reproductive stage, it will develop male pollen sacs. The female plant will produce flowers ready to accept the pollen. This also means that cannabis is not true to seed,

Sexing Cannabis: Is My Plant Male or Female?

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.

Related post

Effects of Cannabis on the Male and Female Reproductive System, and Fertility

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.

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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 You Tell if a Cannabis Seed is Male or Female?

W hen it comes to growing cannabis, sex is important. Not that kind of sex! We’re talking about the sex of the plant, and whether it is male or female. The reason for this is simple enough: only female seeds produce flower, also known as the buds you might have in your stash as we speak.

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Cannabis seeds can be male, female or hermaphrodites. Females produce the resin-secreting flower, and males make small sacs of pollen near the base of the leaves. Over the years, cultivators have learned that un-pollinated females (remember, males produce pollen) continue to make resin as they grow, and flowers that have not been pollinated are much more likely to produce high-potency cannabis. This is the basis of all modern medical and recreational cannabis cultivation, so determining the sex of a plant is highly important. But is there a way to know if a seed is female before growing?

Table of Contents:

  1. Determining if a Cannabis Seed Is Male or Female
  2. What Are Feminized Cannabis Seeds?
  3. Methods for Feminizing Cannabis Plants
  4. Separating Male and Female Cannabis Plants
  5. How Important is Your Plant’s Sex?

Determining if a Cannabis Seed Is Male or Female

The straightforward answer is that, if what you’ve got is a handful of unmarked seeds, it’s pretty much impossible to tell which ones are male or female. The only true way to tell the plant’s gender is to plant a seed, then wait for it to mature.

After a period of several weeks, the plant will begin to pre-flower, or form a small bud in the crux of a branch. One of the first signs your cannabis plant is female is the appearance of pistillates that are wispy and generally white in color. Male plants will instead produce pollen sacs that look rounded with distinct splits running lengthwise, a bit like a tiny crab claw. These are the structures that growers typically look for to determine a plant’s sex.

If you’re looking for more precise, science-based methods to tell your plant’s gender, there are several labs that can sex your plant right after germination – eliminating the lengthy (usually around 6 weeks) wait to learn its gender. Portland, Oregon start-up Phylos Bioscience is in the business of studying cannabis genetics, and they sell a “plant sex kit” that’s pretty simple to do, even for the folks that aren’t scientifically inclined. Simply press a cotyledon, or embryonic leaf, onto the kit’s filter paper and send it to their lab. They then test the leaf for the “Y” chromosome to determine its gender, just as would happen for a human male.

What Are Feminized Cannabis Seeds?

While it’s basically not possible to determine the sex of a seed from a random bag of seeds, a practice known as feminizing is quite popular. Feminized seeds are selectively bred to produce only female plants.

While the process is very effective, it’s not perfect. There’s a chance that a small fraction of the seeds produced via the feminization method will sprout hermaphrodites, which are still capable of producing pollen.

Despite the potential for ‘hermies,’ knowing your seeds are female from the beginning is probably your best bet.

There are many companies that sell feminized seeds, but buyer beware, do your research to make sure the seller is reputable, especially if purchasing online. Thanks to modern technology, most feminized seeds from reliable brands will be 100% female as advertised – but that doesn’t mean there aren’t people selling low-quality seeds out there.

Methods for Feminizing Cannabis Plants

If you have some experience growing cannabis and would like to bend a crop to your will to ensure that the seeds will be female, there are a few feminizing methods you might try. One such technique is to literally stress out a healthy female plant by interrupting the light cycle during flowering, called Rodelization Feminizing.

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In the colloidal silver feminizing method, distilled water is mixed with pure silver and sprayed on female plants. This method works best when the plants are flowering. This results in pollen sacs being formed, which will allow the seeds to produce female plants.

Feminizing via the silver thiosulfate technique involves carefully selecting a nearly mature female plant, then spraying it with a 50/50 mix of sodium thiosulfate and silver nitrate. This triggers a gender change, from female to male. Place this plant back with the others to pollinate other female plants, and female seeds are created.

Separating Male and Female Cannabis Plants

As anyone with seasonal allergies can attest, it only takes a little bit of pollen to have a big impact. The reason that growers are so intent on weeding out male cannabis plants is that a single pollinator can negate an entire potential harvest.

How? The reason is that once pollinated, cannabis plants will cease devoting energy to growing flowers and will tell the existing flowers to stop producing resin, which translates to making less buds and less THC. That energy will be devoted to producing seeds instead. Think of the plant as a battery with a set amount of power. When that supply is spent in one area, it won’t be available for another.

Now consider that a single male plant can spread its pollen to an entire room of females.

If a grow is accidentally pollinated, that means the resources that were spent to bring the plants to that stage — the water, soil, electricity, fertilizers, not to mention the price of the seeds themselves — will have been wasted growing weed that can’t be smoked.

All of those male plants will have to be carefully separated from the grow space and destroyed, or else the growers risk another disastrous accidental pollination. It takes minuscule amounts of pollen to pollinate a plant, so growers must take extensive precautions to eliminate potential contamination. In addition to helping mitigate other contaminants, this is one of the main reasons that many workers will don full-body suits when working in a grow room, ensuring that accidental pollen exposure is kept to a minimum.

How Important is Your Plant’s sex?

How much time you want to spend figuring out the sex of your cannabis plants really depends on how much time and energy you’d like to devote to growing your own marijuana. If you are a medical cannabis patient or caregiver, for example, and need to know what kind of cannabis you are getting every time to keep a reliable supply, buying feminized seeds from a trusted seller is the way to go. It may even be worth it to have your plants tested for sex before they mature. However, if you have some time, consider yourself a green thumb, and want to experiment with your grow, you could simply plant your seeds and see what comes up. Happy growing!

What are your thoughts on feminized seeds? If you’ve used them before, how did it go? Share your experiences in the comments below.

Author

Erin Hiatt is a New York City-based writer who has been covering the cannabis industry for more than six years. Her work – which has appeared in Hemp Connoisseur Magazine, PotGuide, Civilized, Vice, Freedom Leaf, MERRY JANE, Alternet, and CannaInvestor – covers a broad range of topics, including cannabis policy and law, CBD, hemp law and applications, science and technology, beauty, and psychedelics.

Erin’s work and industry insights have been featured on the podcasts The Let’s Go Eat Show, In the Know 420, and she has appeared as a featured panelist on the topic of hemp media. Erin has interviewed top industry experts such as Dr. Carl Hart, Ethan Nadelmann, Amanda Feilding, Mark A.R. Kleiman, Dr. James Fadiman, and culture icons Governor Jesse Ventura, and author Tom Robbins. You can follow her work on LinkedIn, WordPress, @erinhiatt on Twitter, and @erinisred on Instagram.

Sexing Cannabis Seeds

Sexing cannabis seeds is vital for success. Whether a sensimilla grower or seed breeder it is important to know the boys from the girls.

Male vs Female Cannabis

Cannabis is a dioecious plant, which means it has male and female flowers on separate plants. When the male plant enters the reproductive stage, it will develop male pollen sacs. The female plant will produce flowers ready to accept the pollen. This also means that cannabis is not true to seed, i.e. seeds from a cross pollination will not directly represent the flowers they originated from and instead contain genetic material from both the mother and father plant. Because cannabis has both male and female sexes, you need to identify and understand the differences. Cannabis gender cannot be identified by seed or growth patterns and the only reliable method is to observe the reproductive organs that develop.

Growing for weed or seed

When you begin your growing journey, you will need to decide what your goal is. If you want to grow flowers for consumption or processing, you will want to ensure you only grow female plants that do not get pollinated. Seedless cannabis flowers are referred to as sensimilla and are more potent and flavourful than seeded cannabis flower. This is because when the female plant is pollinated, it stops directing energy to producing oils and cannabinoids. Instead, the pollinated plant focuses all its’ energy on producing seeds. Seeded cannabis is undesirable for medicinal and recreational growers yet it is first prize for many hemp and food crop growers, as well as breeders.
If you want to create seeds, you need to grow both female and male plants. You can separate your male plant as it starts to produce pollen. Then collect the pollen and pollinate only one or two branches on your female plant. By doing this you can enjoy the fruits of your labour and produce seeds for the next season. The other option is to simply let a male or two pollinate all the plants over the growing season. Leading to a harvest of hundreds to millions of seeds.

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Sexing Cannabis Seeds

The best way to identify your plants gender is to wait until it is sexually mature and inspect the nodes or growth points. Plants show sexual maturity by displaying alternate branching and “pre-flowers”. These traits begin in the early flowering stages or late vegetative stages. Pre-flowers are reproductive organs that begin developing before the plant fully enters the reproductive stage and can be used as early identifiers. Male plants produce pollen sacs which look like round balls hanging off the plant.

Female plants produce bracts and white hair like pistils. Pollen sacs are rounder in structure where bracts appear more angular with a thin white pistil growing from within. It is wise to wait until you are entirely sure of your plants’ sex before deciding what to do with it. Not all plants produce the same looking organs and early identification can be tricky for some cultivars. Paying careful attention at all stages of growth will ensure that you are able to far better control the quality and results of your grow.

Cannabis sex isn’t that simple

As if cannabis isn’t woke enough, it can also occasionally be gender fluid. In cases of poor genetics, stressful environment or purposeful reversal, the cannabis plant can display both sexes at once. This is called an intersex trait or “hermie”. Hermies are traditionally undesirable as they may seed crops that are intended to be seedless. Thereby greatly reducing the value of the crop.

However, in recent times breeders have perfected the art of using these traits to their advantage. Femisied cannabis seeds are created by forcefully introducing intersex traits in a female plant. Then using its pollen to pollinate other stable clones of the same female plants. This means that the seeds made from the cross will be identical to the mother plant and almost always female. These are known as feminized seeds. Nowadays most breeders will use chemicals to induce this change in the plant, however almost any stress of the right intensity can induce intersex traits across the spectrum.

It’s easier than ever

Always ask first. If you are unsure about sexing cannabis seeds, there are many online resources you can draw from. Facebook groups make a great place to share and learn from others. Similarly online forums are an excellent resource to browse and interact with other growers without compromising your anonymity. But be warned, there are as many unhelpful opinions as there are helpful. As not all comments are from experienced growers. Try and find a community of people whom you feel comfortable with and have a healthy track record.
You should always source your genetics from reliable and trustworthy providers. There are few things more frustrating than finding an unwanted hermie a few weeks from harvest. In South Africa it is now very easy to access high end and reliable genetics. Whether you want to start from seed or clone, there are multiple vendors supplying feminised seeds and clones. For the aspiring breeders, some vendors even supply regular seeds and male pollen that you can apply at your convenience.

Get the right grow gear

There’s an old proverb about not building your house on the sand and how you should plan for success. Growing A+ cannabis requires a dedication and flexible budget for the happiest results. Don’t be afraid to invest a little bit in the correct grow medium and nutrients, it will make all the difference.
We hope that we have taken some of the mystery out of sexing cannabis seeds. Honestly though, it will be surprisingly easy to get the hang of sexing cannabis seeds in no time at all. You will spot the signs and differences quickly with a well-trained eye and should be well on your way to beautiful big buds. If you still need a little help spotting the boys from the girls? Please contact our grow pros for some top shelf advice.