Sexing Weed Seeds

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It is critical that you know how to identify which of your plants are male vs female. This guide will explain cannabis gender & reproduction. 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)! Save up to 8 weeks and reduce operational costs by up to 20% with the LeafWorks Cannabis & Hemp DNA Sex Test. Identify male cannabis & hemp plants as early as 7 days post germination. The LeafWorks Cannabis & Hemp DNA Sex Test is 99% accurate.

Sexing marijuana plants & reproduction

Understanding marijuana gender and reproduction is essential to achieving the best possible harvest. However, it can be confusing.

For marijuana growing success you need to know what feminized seeds are and how to identify your plant’s gender.

This guide will explain these cannabis reproduction topics, as well as other important fundamentals such as what are hermies, and why so many people love sinsemilla.

We’ll also share some ideas on how to make a male plant female.

Cannabis gender identification & reproduction guide

Cannabis plant reproduction

First, let’s talk gender. Unlike most flowering plants, cannabis plants are dioecious, meaning there is a separate male and female plant, similar to humans.

Every plant possesses two pairs of sex chromosomes, X-chromosomes and Y-chromosomes.

Male plants have XY chromosomes, while female plants have XX chromosomes. Also, like humans, there is a natural 50/50 split between males and females.

There is a significant difference between the gender of marijuana and humans, however.

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This is because a marijuana plant can also be hermaphroditic. This means a single plant can have both male and female genitalia (a pistil and stamen).

Unlike humans, a cannabis plant’s gender depends not just on its genetics but also on environmental factors.

That is one reason why, when growing marijuana, you should be familiar with the different traits of female versus male plants.

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Each gender has unique qualities that may or may not be desirable in your garden.

Identifying males and females

It is critical that you know how to identify your male and female plants. However, it can be a bit tricky because cannabis plants do not start with gender.

Plus, they won’t truly reveal their gender until they start receiving 12 hours of darkness every 24 hours. In some cases, that is too long to wait.

Why do you need to know?

The simple reason is this:

Females produce THC and males distract them from it. Therefore, you want to determine the sex as soon as possible so that the males do not fertilize the females.

To explain it further:

Females without seeds (sinsemilla) have higher levels of THC, whereas males produce significantly less THC.

Preventing pollination, therefore, is the best way to ensure the highest quality buds.

Knowing what to look for

In terms of identifying between the two, in general, males have flowers, while females have pistils. Males tend to be taller as well.

All marijuana plants have flowers at some point. However, if you can’t differentiate between males and females on height alone, then flowers and pistils are good indicators.

This may seem simple, but to be honest, identifying the sex of a cannabis plant can be hard.

This is because marijuana plants don’t disclose their gender until they are mature enough to do so.

In fact, you may not know until your plants are almost ready to begin pollination.

If you wait this long to identify the sex of your marijuana plants, then it’s probably too late to grow sinsemilla buds.

Female cannabis plant

Female plants are often very recognizable. While both males and females will form flowers, the flowers from female plants usually do not bloom until after the males.

The females’ flowers will look like sacs that grow two stigmas (they sort of look like feathers) out of them.

Here are two features of females:

  • They eventually open to form little yellow, cream or white flowers
  • They have hairy, whitish pistils that trap pollen from males

You’ll find the stigmas in a node region of the main stalk. This is where a branch grows from the main stem, or where a branch grows from another branch.

Male cannabis plant

The easiest way to identify a male is by its rapid maturity. Males mature faster than females, meaning they will grow quicker and become taller about two weeks before a female plant. This is so they can drop pollen on female plants. Their flowering phase can begin as much as a month before females, giving growers some time to identify them.

Despite what you may have been told, male cannabis plants are not completely useless.

Obviously if you are growing a crop to smoke or sell, then you want females.

If you’re growing for the purpose of making hemp, the male plants make for a softer fiber, which is great for making clothing. Male plants also produce far more seeds, which you need to grow more plants.

Here are some typical features of males:

  • They tend to grow straighter and don’t develop as many flowers as females.
  • The flowers are generally located at the top of the plant.
  • Unlike the female flower, male flowers are tight green clusters.

The male flower has a central part that looks like petal-shaped objects, five of which are inside of the sex organs.

To the untrained eye, they look like a tiny banana bunch. Male flowers are sometimes called “false buds” since they are actually pollen sacs.

These clusters begin opening over time until a stamen appears – ready to pollinate the females.

Preflowers

It is challenging to identify the sex of a cannabis plant-based on flowers. This is because there is a very short window between when they appear and when the plant is fertilized.

Instead, expert growers do this to identify sex:

They focus on finding the preflowers. These develop at the tips of branches and on the main stem. Preflowers are the immature first flowers that proceed the mature flowers.

Basically, it works like this:

If you notice a raised calyx on a small stem or stalk, then it is most likely a male. If this calyx isn’t raised, then it is probably a female plant.

Yes, it’s that simple. It can be hard to see the difference at first, but over time, every grower gets better at it.

Other methods for identifying the sex of your plants

Sometimes, you want other options. Maybe you need to know sooner, or perhaps you just prefer to use a variety of methods. Here are a few other ways to identify the sex of your plants.

Look at the growth patterns.

During vegetative growth, every plant, regardless of sex, starts to flourish. As the plants age, however, you will notice subtle differences in their sizes.

Some marijuana growers have even noticed certain signs early on that can help determine the sex.

Females tend to have more complex branching when they progress from the seedling stage to the vegetative stage. Males, on the other hand, tend to be slightly taller and less filled out.

This method is not foolproof, and you shouldn’t use it as a reason to throw out a plant.

Of course, the last thing you want to do is pull plants out at this early stage.

There is a reason to try it, however. It can help you get an idea, so you know which plants to watch later on.

(Note: this works best on outdoor grown plants, as those grown indoors under artificial light don’t usually exhibit these tendencies).

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Identify where the plant sprouted during germination.

Need to know as soon as possible? Some marijuana growers have discovered a method that identifies the sex of the plants just after germination.

According to their theory, if the sprout comes out of the top or bottom of the seed, it is generally a female. Side sprouts, on the other hand, generally turn out to be male.

While this hasn’t been scientifically studied, growers who have used this method report a 90% success rate.

Even with this anecdotal evidence, you shouldn’t use this as absolute fact. Let the plants grow a little and try to notice any distinctly male or female signs.

Don’t just throw away the marijuana seeds simply because they sprouted out of the sides.

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Instead, keep track of your predictions so that you can make an informed decision later.

Clone your marijuana plants.

This is really the only foolproof way to determine the sex before the plants achieve maturity.

The best part about this technique is that it is easy. You merely take a cutting from one of your plants.

Cloning in 3 steps:
  • Cut a small piece of the mother plant
  • Place the cutting into potting soil and let it grow
  • Force flowering with 12hr darkness/12hrs light after a few days

To identify the sex of your clones, you’ll need to keep them separate from the host plants.

This method works because, since they have the exact same DNA as their host, they will have the same sex.

Once the clones go into the flowering stage, it will be easy to determine their sex and the sex of their hosts.

Make sure you keep track of which clone came from which host, so you don’t get things mixed up.

You can also force the flowering of a regular plant (not a clone) and put it back into the veg stage once you know it is female.

However, this process can cause more trouble than it is worth. While effective at speeding up the reveal process, it can also place unnecessary stress on a developing plant.

Flowering and reproduction

Once your plants have developed their sex, they are ready for reproduction.

Here’s some detail on what happens during that process.

Also, when the plant is fully grown, you can start thinking about Harvesting! Download my free Harvesting Guide here.

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Female flower formation

On a female marijuana plant, a large cluster of buds appears. This cluster is called the cola, and it consists of many sub-units of buds.

Within the cola, there are many pistils, which moderate the female processes of reproduction. Each pistil contains the stigmas that interact with male pollen.

Throughout the flowering process, cola is preparing for reproduction. The plant stretches and develops its bud sites.

These sites house groups of female marijuana flowers seeking to be fertilized. New flowers form on the top side of these subunits, and small stigmas emerge from the pistils.

These thin structures are often recognizable by their white hair.

They can still be pollinated even if they are not white.

Stigmas can sometimes die – especially after heavy rains or wind. This will cause them to become dry and change in color from brown to red.

This does not mean that pollination cannot happen. Even if a stigma is this color (instead of white), it can still receive pollen.

The female flower also has other hairs – glandular trichomes. These “hairs” are responsible for producing resin on the flowers and nearby leaves.

Up close the resin looks like a ball attached to a tiny neck. Its shape is a good indicator of how delicate they are.

If you handle the buds roughly, some of these trichomes can break off.

Underneath the pistol, you will find a smaller leaf called the stipule. It is more noticeable before flowers are formed.

Once the plant is fully grown you will need to start thinking about harvest time.

Our free little Harvest Guide will help you determine the best moment to cut your plants. Download it here.

Awaiting pollination

When a male marijuana plant matures, it releases pollen and seeks out the female stigmas.

The pollen then travels to the egg cell located inside of the pistil, producing a seed. If this process does not happen, the female flower begins to change.

The fact is, Cannabis plants are designed to pollinate.

The pollen from a male plant can survive for a few days as it attempts to reach a female, increasing the cannabis plant’s chance of survival.

Pollen can survive on fabrics, and in air ducts. It can also be stored for intentional fertilization.

Female plants also do their best to be fertilized. Pistils grow larger when they are not fertilized. This is so they have an easier chance of locating pollen.

However, this effect does not last forever. When the pistils are completely mature, the stigmas will die, and they cannot be fertilized.

At this point, resin production will slow down or stop, and the trichomes will begin to break down.

The last opportunity for fertilization marks the beginning of the plant’s death, but it is not immediate death.

Pistil maturation occurs gradually, instead of all at one time, leaving growers plenty of time to harvest.

What about autoflowering seeds and plants?

Most standard marijuana plants start to flower at the end of summer as days start to get shorter and the amount of light drops.

Regular plants recognize that they need to start maturing before the onset of winter, but autoflowering plants are different.

They will enter the flowering stage even if they receive a full 24 hours of light.

An automated flowering period is great for growing in places with unusual growing seasons, or when you’d like to harvest twice in a single growing season.

This is because a decrease in daylight hours (typically triggered by the change in seasons) is not needed for these plants to flower.

Feminized autoflowering seeds provide the dual benefits of a quick harvest and not needing to identify plant sexes.

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Autoflowering marijuana seeds also produce plants that are generally small and ideal for outdoor growth. With these, you can plant a couple for every square foot.

Plus, they only take about 10 weeks to harvest. That being said, the yield and quality are not up to par with seeds that flower regularly.

The features of autoflowering plants
  • Generally, 12 to 23 inches tall (30 to 60 centimeters)
  • Suitable for outdoor growth
  • Starts flowering automatically after around 3 weeks
  • Yield between 0.5 to 2 ounces depending on hours of sun
  • Goes from seed to harvest in about 9 to 10 weeks

Autoflowering seeds will yield between 50 and 500 grams per m2, but this depends on how well you care for your plants.

Prevent fertilization with feminized seeds

Many growers prefer cannabis that is not pollinated and does not have seeds. It is called sinsemilla, which is Spanish for without seed.

Because these plants did not produce seeds, their plants tend to have more trichome production and more potency.

Feminized seeds help prevent fertilization by ensuring your seeds grow into female plants. If there are no male plants nearby, your female plant will not form seeds.

Many growers try to prevent pollination. Here’s why you should consider growing sensimilla using feminized seeds.

Save the energy for the buds

Pollination means that the plants will use their precious energy for creating seeds instead of flowers. This has evolved due to natural selection.

Since a plant that produces more seeds is more likely to reproduce many future plants, the trait is passed on.

Although this is an advantageous feature for marijuana’s survival, it is not exactly what smokers are looking for in a weed plant.

When female plants grow into maturity without being fertilized with male pollen, they can usually produce a more resinous bud. This is because there are no seeds to take over the valuable flowering area.

Sinsemilla is difficult to grow

Sinsemilla weed is expensive not just because it is high quality. It’s also because preventing pollination is hard.

Your female plants could be pollinated by male plants from up to a mile away!

You could also simply identify the sex incorrectly or wait until it’s too late to separate the males from the rest of the marijuana crop.

If you make a mistake, don’t freak out.

While seeds aren’t always wanted, accidental pollination frequently occurs. If you are worried that it has happened to you, look for swollen calyx rings (beneath the stigmas).

If unintentional pollination occurs, remember that a few seeds won’t ruin a harvest.

After all, it may only be one flower, and your plant has hundreds of them. You can either pick those seeds off or leave it alone.

A few seeds aren’t bad

Although you probably don’t want them, producing a few seeds isn’t necessarily a bad thing.

If one crop is particularly delicious or potent, you want those plants to produce a few seeds.

Store these seeds correctly and label them accurately so that you can identify which seeds produced the best crop later. Then, use the seeds that produced the desired traits in a future growing season.

Now that we understand the flowering stages’ role in marijuana reproduction let’s go more in-depth into the different sexes.

The female marijuana plant

Female marijuana plants take a tad bit longer than males to reach sexual maturity. But once they do, it is quite easy to spot them.

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During the pre-flowering stage, the female plant will grow one or two wispy white hairs where buds will form. It means that the plant is ready to bud anytime soon.

The hairs will be visible on the main stem that connects to the nodes or branches. Once the hairs are spotted, that is a great sign that the plant is a female.

Ensuring female plants

Female plants tend to start showing hairs even before the flowering stage, or changes in grow light schedules, but they can still be fertilized by a single male. Most growers dream of having an all-female garden. This way they won’t have to deal with removing half their plants when they reveal themselves as male. This is where feminized seeds come into play.

Feminized seeds help improve your chances of growing female plants.

Feminized marijuana seeds are seeds that only produce female marijuana plants.

But they aren’t the only thing that makes a cannabis plant female. Under some conditions, female (and feminized) seeds can become hermaphrodite plants and fertilize themselves.

How feminized seeds are created

Are you wondering how breeders create a female seed? Here’s a summary.

Early methods

Early feminized marijuana seeds usually were made with two female marijuana plants.

One of the plants would have already shown hermaphrodite tendencies, i.e., prone to produce male marijuana flowers when it was stressed.

The intersexual-prone marijuana plant is then stressed by light cycle interruption or pruning. The stress would encourage them to produce male marijuana flowers.

Then, the pollen from the hermaphrodite plant is applied to the ‘true’ female (i.e., a plant that did not easily display intersexuality when stressed).

The downside of this method is that the female marijuana ‘pollen donors’ already had quite a strong tendency to turn intersexual.

That tendency, in turn, was very likely to be inherited by the resulting feminized seeds.

Current methods

In the early days of feminized marijuana seeds, hermaphrodites were a reasonable concern, but nowadays hermaphrodites formed from feminized seeds alone are rare.

Today, breeders use a technique called rhodelization. It uses different forms of silver to force female plants to produce male flowers.

This new, more intensive, technique produces stable and consistent seeds. Now, female plants with a very minor tendency to turn intersexual can be used, instead of the hermaphrodite plants needed in the past.

Best of all, none of the genes are modified, so the seeds produced are female.

These female plants stay female even when placed under harsh, irregular, or stressful conditions.

This means that their offspring have no more tendency that a normal female marijuana plant to turn intersexual.

If anything, the parent marijuana plants are physically modified by silver, and the seeds are produced naturally, through pollination.

Cannabis Pre-Flowers: Identify Sex of a Plant as Early as 3 Weeks Old (with pics!)

The female plants will soon produce pistils. Wispy white hairs are a sure sign that you’re looking at female pre-flowers.

How to Determine the Sex of a Young Cannabis Plant

What are cannabis “pre-flowers?” They are little versions of adult flowers that appear on your marijuana plants relatively early in the vegetative stage.

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.

Cannabis Pre-Flowers Are Small Versions of Adult Flowers. These reveal a plant’s sex.

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”).

Cannabis pre-flowers appear at the base of leaves when male plants are about 3-4 weeks old, and female plants are 4-6 weeks old.

Even if you’re not 100% sure about every plant from looking at the pre-flowers, it’s nice to know which plants you need to watch closely and which are definitely female. However, if precision is very important…

Chemical Leaf Tests Can Determine Sex & Potency for plants as young as 1-3 weeks

Chemical leaf testing is getting less expensive every day and can be used on cannabis seedlings with just a few sets of leaves to test for sex and future potency.

These tests only require a tiny amount of plant tissue (for example a small punch-out from a leaf, or a single cotyledon leaf), so it won’t hurt or slow down your seedlings to take a test sample!

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.

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.

There are many reasons growers would like to know plant sex as early as possible, as well as be able to estimate the overall THC/CBD ratios of future buds!

Did You Know? There are Chemical Leaf Tests that Can Definitively Determine Both Plant Sex & Future Cannabinoid Ratios of Very Young Marijuana Seedlings!

But for those of us using our eyes…

Male Pre-Flower

Female Pre-Flowers
(these turn into buds)

This female pre-flower hasn’t released a wispy white pistil quite yet

When starting with “feminized” seeds (which you can usually only get from a breeder), all your seeds should end up being female, so determining male from female isn’t very important. Learn more about buying seeds (including feminized seeds) from breeders online.

But for growers starting with “regular” (non-feminized) seeds, about half of the plants can turn out to be male. And unfortunately, there’s no way to look at a seed and be able to tell what sex it is.

Unfortunately, you can’t tell a cannabis plant’s sex for sure by looking at the seeds

How to Figure out Sex of a Cannabis Plant by Examining Pre-flowers

Vegetating plants usually reveal their sex when they’re just 3-6 weeks old from seed, but you have to know where to look.

What you’re looking for is “pre-flowers.” These are tiny versions of adult sex parts, and when you see them you can tell what sex the plant is going to be. They usually show up in the upper parts of the plant, closer to the lights, but sometimes you’ll search the whole plant and only find a pre-flower on a random branch lower down on the plant.

Vegetating cannabis plants reveal their sex with “pre-flowers” that usually appear 3-6 weeks from when the plant first germinated.

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.

Most male plants have grown a pre-flower by week 3-4 from seed, while female plants don’t show until week 4-6. Basically, all vegetative plants will have revealed their sex by about the 6th week from seed.

So, without further ado, here are pictures showing what you’re looking for when it comes to pre-flowers. Remember, pre-flowers are found at the V where stems meet a main stalk. But pre-flowers don’t usually show up all over the plant. Make sure to look around in different places, especially near the top of the plant and closer to the lights

Note: Pre-flowers show up most often near the top of the plant and closer to the lights but could be anywhere on the plant. There may be just one on the whole plant so you may have to search all over!

Male Pre-Flowers

Male pre-flowers tend to have a “spade” shape, like the spades from a deck of playing cards. Male cannabis plants often (but not always) reveal their sex sooner than female plants.

Male pre-flowers tend to be shaped somewhat like a spade

This male plant was only 3 weeks when it made its first pre-flower. Notice how tiny it is compared to the giant-sized thumb! Often it’s unclear what the sex is when a pre-flower is this small (unless you’ve got a lot of experience) so if you’re not sure, it’s a good idea to wait and see how it develops, just in case.

Just to give you an idea how small these can be when they show up…

This is the exact same picture as above, but with the pre-flower made bigger so you can see it. Pretty tiny, isn’t it?

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Male pre-flowers are basically immature pollen sacs. When the plant starts flowering, they will grow and turn into bunches that almost look like grapes.

I’ve also noticed that sometimes (though not always!) the stipules on male plants seem more “leafy” and less “pointy” than stipules on female plants (the stipules are the green hair-like growths near where pre-flowers show up). However, this is just a generality, and should be used together with other factors to determine if a plant is male! There are definitely male plants with pointy stipules and vice versa, but it’s sort of a general difference.

This particular pre-flower is really tough to determine. However, in the end, it was a male plant. The little “stem” is one clue it may be male

Just like the above male plant, sometimes you get almost what looks like two tiny little leaves that the pre-flower pollen sac “unfurls” from. In the above picture the pollen sac is still mostly hidden, while in this next picture, the tiny growths have opened up to fully reveal the pollen sac. This can be confusing because these extra growths don’t appear on all plants, and are not a pre-flower or a stipule.

Here’s another male pollen sac pre-flower that’s on a little “stem”

A single male pre-flower appears

Once you see multiple pollen sacs and no white pistils, you can be confident it’s a male plant

Although this plant ended up being male, the stipules are long, pointy and crossed as you’d normally see with a female plant. That’s why you need to confirm sex with the pre-flowers and not just look at other factors on the plant!

Sometimes the pollen sacs look a little unusual when they first start growing in, but you know it’s male when you see several pre-flowers without any pistils stacked on top of each other like bunches of grapes

If you click the following picture and zoom in close, you can see pollen sacs scattered among the leaves

This is what male pollen sacs look like when the plant actually starts flowering

This male cannabis plant has gotten further along in the flowering stage

This is what a male plant looks like at maturity when it’s starting to spill its pollen

Another example of pollen spilling onto a nearby leaf

For those who’ve never seen a male cannabis plant in its full glory

Ok, now that you know what male pre-flowers look like, what do female pre-flowers look like?

Female Pre-Flowers

Female pre-flowers tend to be longer and narrower than male pre-flowers, sometimes with a fat bottom. They also usually (but not always) have 1-2 white hairs (pistils) sticking out from the top. Sometimes it takes a few extra days for the pistils to appear.

Wispy white pistils are a sure sign that you’re looking at female pre-flowers

This pre-flower doesn’t have a pistil sticking out at first, but the shape helps tell you it’s a female plant. If you’re not sure about sex after spotting a pre-flower, it’s a good idea to wait and see for a little while, just to see if a white hair appears (which means it’s definitely a girl)

Another example of female cannabis pre-flowers that haven’t revealed their pistil yet

Here’s a picture that shows a pistil right as it’s emerging from the calyx!

If the pre-flower is very pointy and thin like this one on the right, it is often a female pre-flower

Some of the time the stipules (green hair-like growths near where pre-flowers show up) will cross each other on female plants. This certainly doesn’t always happen, as you can see from the pics of female pre-flowers on this page, but while girls can go either way, male plants rarely have stipules that cross each other. So although crossed stipules cannot be used definitively as a way to identify female plants, it can be a small clue to help guide you when you’re not sure. For example, the following female pre-flower doesn’t have a pistil, but the long thin shape combined with the crossed stipules help indicate that this plant is a girl. Whenever in doubt, wait a week and look again!

This female plant has a long, thin calyx and crossed stipules, which are typical female plant features

In this pic, you can see white pistils emerging from the calyxes. Female pistils are white and wispy, never green.

Here’s another female pre-flower that doesn’t have a white hair yet, but you can tell it’s female because it’s long and narrow, instead of spade-shaped

One last female pre-flower without a pistil yet. The long narrow shape is the only thing that gives the sex away until pistils begin to emerge

Super close-up picture of a female cannabis pre-flower

Female cannabis calyxes with pistils, under an LED grow light

Did you know that pre-flowers/calyxes/flowers are actually what holds seeds if your plant gets pollinated? Once pollen touches the white pistils, the pollen gets delivered to the inside and a seed starts forming!

Variability of Cannabis Plant Sex – How to Increase Ratio of Female Plants with Regular Seeds

In fact, to this day scientists are still not sure exactly what causes certain plants to be one sex or another after sprouting. We’ve identified several factors that predict the overall likelihood of male/female plants (for example feminized seeds always produce female plants no matter what), but sex seems to be somewhat fluid in cannabis plants when they’re first germinated.

Certain conditions such as excessive heat, stress, unusual light periods and nutrient problems can cause a greater percentage of plants to produce male flowers.

You may be able to increase the percentage of female plants with regular seeds during the first few weeks of life

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

  • Healthy Mom – Only grow seeds from a vigorous, healthy mother plant who never showed any signs of herming or male pollen sacs (seeds are more likely to grow pollen sacs if the mom plant had a tough start in life, or hermed during the flowering stage)
  • Cool Temperatures – Give seedlings slightly cool temperatures (65-75°F day and night) and avoid excessive heat
  • High Humidity (50-70% RH)
  • Short but not too short days. Keep consistent day and night periods with no light interruptions at night, and days should be 14-18 hours long (between 14/10 and 18/6) for the first few weeks
  • Blue light. Always start seeds under a vegetative grow light (something with plenty of blue like a Metal Halide or a 6500k CFL/T5/fluorescent)
  • Avoid Deficiencies – Make sure to provide plenty of Nitrogen and don’t let seedlings become nutrient-starved or run into other types of deficiencies
  • Prevent Stress, especially heat or light stress during the first few weeks
  • Happy Roots – Avoid over (and especially) under watering

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.

Unfortunately, due to the fact that different environmental conditions during the first part of life can alter the sex, you can’t look at seeds and definitively know one way or the other whether the plant will end up being female because even the plant doesn’t necessarily “know”.

For example, say you take a clone of a seedling before it’s 3 weeks old. It’s possible that one clone will be male, and the other clone will be female. However, if you take a clone after week 3, the sexes of clones will always match each other. This is further evidence to indicate that the environment can affect sex expression in some cases.

LeafWorks Cannabis & Hemp DNA Sex Test

Want to identify male cannabis & hemp plants early in the growing cycle?

Save up to 8 weeks and reduce operational costs by up to 20% with the LeafWorks Cannabis & Hemp DNA Sex Test. You can identify male cannabis & hemp plants as early as 7 days post germination.

The LeafWorks Cannabis & Hemp DNA Sex Test is 99% accurate and because we use more biomarkers than the competition, we greatly reduce false positive test results allowing you to confidently remove male plants quickly.

  • Turnkey collection and submission kit is provided for every order
  • Simply mail your cannabis or hemp plant samples using the collection cards provided
  • Up to 4 plants collected per card
  • National and international orders accepted
  • Tests available for licensing
  • Order up to 25 cards: $60 per card; only $15.00 per plant
  • Order 25 to 250 cards: $50 per card; only $12.50 per plant
  • Order over 250 cards: $40 per card; only $10.00 per plant

3-7 business days after the lab receives your samples, depending on volume of cards to be processed.
LeafWorks only accepts samples through the LeafWorks DNA submission kit. We will not test or receive Schedule I tissue.

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