How To Sex Marijuana Seeds

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The best Marijuana Seeds selection, from the finest sativas until the most medicinal Indicas, discover them in Delicious Seeds. 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)! Determining the sex of cannabis seeds. How to tell female from male weed seeds? Check it out!

How to know if a marijuana plant is male or female

How to know if a marijuana plant is male or female

Cannabis sativa sp, that is, the marijuana plant, is a dioecious or unisexual specimen. This means that it is a plant that produces both male and female flowers on different plants. However, there are also marijuana plants that are hermaphrodites, so they will be able to produce male flowers and female flowers on the same plant. Sexing marijuana plants allows you to separate the male from the female. The division has nothing to do with not getting along, but to maximize your harvest. Pay attention to us: boys with boys and girls with girls. Today we are going to talk to you about how to sex your marijuana plants and how to know which ones are male and which are female as soon as the flowering cycle has started.

12×12

The flowering of cannabis plants begins as soon as it receives 12 hours of uninterrupted light and 12 of darkness in each of the 24-hour cycles. These cycles are known as photoperiod and allow the plant to enter a pre-flowering stage in which they increase in size to facilitate the branch to support the flowers preparing their structure.

Pre-flowering, what will it be? What nerves!

The pre-flowering period usually lasts for about 10 days. Taking into account that the flowers should appear after two weeks, in the pre-flowering period it is not possible to know if a cannabis plant is male or female. In the case of feminized cannabis seeds or automatic cannabis seeds, this question no longer has a place, since they are plants grown to flourish as females.

How to sex marijuana plants?

Surely you have heard of the 12×12 light and dark methods or the 6pm light and 6h dark methods. This method is done with the mother plants and the process will depend on whether you are growing plants indoors or outdoors. The trick, in both cases, is to induce flowering to sex the marijuana plants. Indoors you can decide when to alter the photoperiod and artificially induce flowering. The process is very simple. Simply set the light timers to force the plant to produce the flowers ahead of time. Outside, things are not so simple. In these cases, it is necessary to wait until the hours of natural light have been considerably reduced. In fact, up to about 12 hours a day. Obviously, there is no exact rule for the precise moment when this will happen, since it is directly dependent on the area in which you live. If it serves as a reference, in northern Europe, the decrease to 12 hours of light a day occurs between mid and late July. When this happens, it is possible to induce the flowering of cannabis plants outdoors by exposing them to light during those 12 hours and covering or protecting them in an indoor area after that period of time. One of the difficulties with this method is that it requires consistency. Exposure to 12 hours of daily natural light should be done every day without fail. In the event that the periods of darkness are interrupted by an episode of light, a negative effect can be generated in the marijuana plant and immediately return it to an uninteresting vegetative state. In any case, we tell you this to improve your general culture, not for you to try to do it. Obviously, we cannot forbid you anything, but we can warn you that this type of method causes important hormonal changes inside the plant and induces stress, which could lead to hermaphroditic plants that would destroy your sexing plan for marijuana plants. If you are a little patient, your cannabis plant will reach its state of sexual maturity between six and eight weeks after germination without you making any changes in its photoperiod and there you will be able to recognize its sex. Removing some cases of hermaphroditism caused by stress, the marijuana plant will determine its sex for life once it reaches the cycle of the fifth or sixth stage of leaves and that is when you can sex your plants without any doubt. Our advice? Be patient and pay attention to the maturation of the plant to know the sex without resorting to modifying the photoperiods that can cause stress on the plant or cutting methods.

How to recognize the marijuana plant

Male marijuana plants have little bells grouped in panicles when they bloom. These bells hang down and open to release pollen, unlike female marijuana plants, which bloom through teardrop-shaped calyxes from which two white pistils emerge, clumping together and forming what we commonly know as buds. Or cogollazos if you are lucky and grow a luxury specimen.

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.

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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?

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.

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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
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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.

How to Tell Female from Male Weed Seeds?

Determining the sex of your cannabis plant is very important. Most growers require female plants because these are the ones that produce the resiny buds we love. Males, by comparison, simply produce the sacs of pollen used to pollinate female strains to produce seeds. Female varieties shouldn’t be pollinated. Otherwise, they will no longer produce their THC-laced resiny buds.

In a regular growing setup, males have to be removed as soon as they’ve spotted to reduce this risk of pollination. Otherwise, you run the gamble of turning your precious resiny buds into seeds and spoiling the whole crop. But can you tell the difference between weed seeds before they’re cultivated?

Can you tell male from female cannabis seeds?

Simply put, there is absolutely no way to tell the difference between male and female cannabis seeds before they’re planted. There is nothing in their appearance or size to indicate what will grow. The only way to tell is to grow it, wait and see.

You can, however, pick up feminized seeds directly from Weedseedsexpress to guarantee a female plant every time. Feminized seeds are bred exclusively to produce female plants. Knowing your seeds are female from the beginning is the perfect solution for hobbyists and smaller setups that can’t waste resources.

If you’d prefer to plant regular weed seeds, experiment and discover the sex of your plant as it grows, you can choose these here too.

Myths about determining the sex from the cannabis seeds’ appearance

There are plenty of myths out there on how to determine if a cannabis seed is male or female. Don’t be duped by them.

One of the most common is that female seeds have perfectly round crater-like impressions under them, just like a volcano. This is false. Crater-like impressions or indents can form on any and all seed varieties, no matter the sex.

Other myths include those pertaining to size and shape. Neither male nor female seeds are smaller or bigger than one another.

What’s more, some have speculated that male seeds are heavier, ragged or protruded, meaning that if you roll them on a table, they thump like a flat tyre. By comparison, it’s supposed that female seeds are smoother and therefore roll easily across a table. This is also false. Any seed can be any shape – it’s got nothing to do with sex.

Finally, there are no other indicators to tell the sex of cannabis seeds. No aroma, weight difference or coloration. If you find a chart indicating such methods of detection online, ignore it. This will prevent you from wasting time cultivating and accidentally pollinating your crops.

What can you do to tell male from female cannabis seeds?

The only way to sex your cannabis seeds is to sow, grow and check. Most female strains begin to show characteristics of their sex after 4 weeks or more, just before the first stage of flowering.

You have to wait out the vegetative stage until the hair-like pistils begin to grow from the stems. This is indicative of the pre-flowering stage and a sure-fire sign of a female plant.

By contrast, male plants show their signs much earlier. Male plants grow sacs within the crevices of stems which are filled with pollen. As soon as you notice these, it’s time to remove them from your crop to prevent pollination. Males typically grow these sacs in as little as 2 weeks, giving you plenty of time to react.

If you’re worried about your crops pollinating without you knowing, there are a few tricks you can use to identify sex early.

Instead of waiting it out and meticulously inspecting your plant, consider placing an opaque black or paper bag over a growing tip on your plant during vegetation. Keep the bag on for 12 hours in a 24-hour period and repeat. This manipulates the light cycle and forces the plant to pre-flower early. You can then check the sex of your plant after roughly 7 days before allowing it to revert.

There are also professional, scientific ways to determine the sex in advanced botanical setups, but aside from mailing off samples to labs, few can try this at home.

Alternatively, feminized seeds provide a more fool-proof strategy for cultivating healthy, resin-producing crops. You’ll have no need to sex your plants early and run no risk of accidentally pollinating your crop.

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