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Cannabis Pre-Flowers: Find the Gender Sooner (with pics!)

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What are cannabis “pre-flowers?” They are little versions of adult flowers that appear on your plants and can help you figure out the plant gender as soon as possible.

Why do you want to find out if your plant is a boy or girl? The reason is because only female plants produce buds, while male plants only produce pollen (which no grower wants to harvest – pollen is only used for germinating female plants, and shouldn’t be smoked).

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 being male. And unfortunately, there’s no way to look at a seed and be able to tell what gender it is.

In fact, to this day scientists are still not sure exactly what causes certain plants to be one gender or another. Gender seems to be somewhat fluid in cannabis plants, as certain conditions such as heat, stress, unusual light periods and nutrient problems can cause more of the plants to show male pollen sacs. Take good care of your garden to ensure the highest levels of bud-producing plants!

Unfortunately, you can’t tell a cannabis plant’s gender by looking at the seeds 🙁

So when growers start out with regular cannabis seeds, they have to be aware of gender while the plant is alive, and try to determine gender as soon as possible. Growers don’t want to spend a lot of time on a plant only to realize that it’s male and has to be thrown away.

All cannabis plants reveal their gender in the flowering stage (the second stage of life, when cannabis plants produce buds or pollen sacs), but for most growers, it’s much more helpful to determine the sex of the plant as soon as possible.

There are a few different methods to determine gender of young, vegetative plants. One is to take a clone of the young plant, and force it to start flowering. The gender revealed by the clone will tell you the gender of the plant it was taken from.

But that’s not the only way to figure out the sex of your plants. Vegetating plants usually reveal their gender 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 gender the plant is going to be. They usually show up in the upper parts of the plant, closer to the lights.

Vegetating cannabis plants reveal their gender with “pre-flowers,” which usually appear 3-6 weeks from when the plant was germinated.

While week 3 is early for most seedlings, nearly all vegetative plants will reveal their gender 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 don’t usually appear all over the plant in veg; they show up the most often near the top of the plant and closer to the lights

Male pre-flowers tend to have a “spade” shape, like the spades from a deck of cards. Male cannabis plants often (but not always) reveal their gender 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 preflower. Notice how tiny it is compared to the giant sized thumb! Often it’s unclear what the gender 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?

Another male pre-flower

These 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.

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

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

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

Female pre-flowers tend to be longer and narrow, and usually, but not always, have a white hair (pistil) sticking out from the top.

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 gender 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)

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.

This female plant has a long, thin calyx and crossed stipules

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 gender away until pistils begin to emerge

Learn how to use pre-flowers to determine the gender of your plant when it’s only 3-6 weeks old from seed. Lots of pics!

What are preflowers?

  • Dec 5, 2007
  • #1
  • SmokeyMacPot
    New Member

    Preflowers, as opposed to full blown flowers, generally appear after the fourth week of vegetative growth from seed. Check carefully above the fourth node. Please note that preflowers are very small and and almost impossible to differentiate without magnification. A photographer’s 10x loupe is handy indeed when examining preflowers.

    As the images below demonstrate, the female preflower is pear shaped and produces a pair of pistils. Frequently, the female preflowers do not show pistils until well after the preflowers have emerged. Thus, don’t yank a plant because it has no pistils. Pistillate preflowers are located at the node between the stipule and emerging branch.

    Also, some female preflowers never produce pistils. A female preflower without pistils is difficult to distinguish from a male preflower. Thus, hermaphodite issues should not be resolved by the appearance of preflowers, without pistils, on a plant otherwise believed to be a female.

    The male preflower may be described as a “ball on a stick.” However, its most recognizable feature is its absence of pistils. Sometimes, a male plant will develop mature staminate flowers after prolonged periods of vegetative growth. These appear in clusters around the nodes.

    The following image shows a male plant in early flowering. Staminate flowers are located at the node between the stipule and emerging branch.

    Preflowers, as opposed to full blown flowers, generally appear after the fourth week of vegetative growth from seed. Check carefully above the fourth node…