Cannabis Sativa or marijuana is a dioecious plant, which means that both males and females can be found in nature. These plants reproduce sexually via pollination of the female by the male; male plants produce pollen from their flowers which go to the females’ pistils. This is how cannabis seeds are formed, which have Y chromosomes and X chromosomes (male and female, respectively). A pure female plant has YY chromosomes, and a pure male plant has XX chromosomes; most plants are XY.

Most growers are looking to grow plants that produce female flowers, as these are the ones which contain the most active substances in cannabis (cannabinoids and terpenes). Nowadays, it’s easy to get feminized seeds, which always produce females, although if you want to grow regular seeds you’ll need to know how to tell the difference between male and female cannabis plants.

How to Identify your Cannabis Plants’ Sex

When it comes to growing cannabis, you can start from clones or cuttings, which are guaranteed to be female as they’re from mother plants and grow with the same characteristics. On the other hand, if you decide to grow from seeds you’ll need to know what type you’re growing in order to identify its sex.

Types of Cannabis Seeds

• Feminized Seeds: these seeds also include most autoflowering strains. These seeds only produce female plants, all of which produce sought-after buds. If obtained from a reliable seed bank, you don’t need to worry if they’re male or female plants, as they couldn’t possibly be male.
• Regular Seeds: they can produce both female and male plants, so you’ll need to be able to differentiate between the two in order to use them according to whatever your goal or objective may be.

Male cannabis plants show their sex through small balls (male flowers) which produce pollen once they open up. On the other hand, female cannabis plants tend to produce pistils, little hairs, that are an intense white colour. However, in order to tell them apart you’ll need to wait for them to grow and begin showing their sex, which we’ll explain now.

Growth Period

Once you’ve germinated your seeds, the growth period starts. During this first delicate stage, your plants put a lot of their energy into growing, producing roots, stems and leaves; they need to develop correctly so that they can then go on to their sexual or reproductive stage.

• A plant obtained from a seed needs at least three weeks to grow so that it can achieve the right size before flowering, as well as to give it time to mature enough to start showing its sex.
• Before those three growth weeks, plants will rarely show their sex. If you have various plants growing indoors, you should give them around 4 growth weeks in order to make sure that they’re mature enough.

Preflowering

The pre-flowering period is what happens between the growth and flowering stages. In indoor grows, this period happens the first two weeks after flipping your lights to 12/12h light and dark.

During this period it’s incredibly easy to distinguish the sex of your cannabis plants, so if you’re looking to harvest flowers, you’ll need to get rid of male plants. Male cannabis plants consume resources, space, light and nutrients, and can also be used to pollenate female plants. A plant with pollenated flowers will generate seeds, which produce a bad flavour and aroma when smoked. Plants also end up spending a lot of energy in creating seeds rather than creating flowers and cannabinoids.

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In indoor grows, pre-flowers appear a few days after flipping the lights. Male pre-flowers are thicker than female ones, as they are growing little pollen sacks inside. Female pre-flowers are more stretched out and longer than male ones. If you still can’t tell the difference, wait a few days to see if pistils begin to appear.

At around 2-3 weeks*, your plants will begin to show small groups of pistils if they’re female plants or small round balls if they’re male plants.

*Plants grow intensely during these few weeks, which means they need to consume large amounts of nitrogen; we recommend using growth fertilizer during the two weeks after flipping the lights to keep your plants growing strong.

In outdoor grows, the reduction in time periods of light and dark happens slowly, so this period is a bit longer; from two weeks to a month. The growth period isn’t quite as intense as indoor grows, therefore flower production is also slower, although there are enough flowering signs so that you can tell the sexes apart; logically, don’t wait until the flowering period starts to identify your cannabis plants’ sex.

Hermaphrodite Cannabis Plants

If your cannabis plant begin showing male and female flowers, this means that it’s a hermaphrodite. There are different degrees of hermaphroditism, and it has a lot to do with chromosomes and the conditions that your plants are in.

• If your plants receive any type of light or environmental stress during the flowering period, they may produce male flowers in response to that stress.
• There are plants that, due to their nature, during the pre-flowering period already start showing male and female flowers; you can get rid of these plants without having to waste much time on them. They may also take a while to show their hermie side, until the flowering stage starts, which makes locating male flowers among the female flowers much harder, and you may end up with accidentally pollinated flowers.

Male flowers can appear towards the end of the flowering period quite often, although they don’t have time to pollenate the female flowers; don’t worry, if that’s the case. We don’t recommend reusing seeds from hermaphrodite plants, as they’ll most likely produce hermaphrodites as well.

Advice

• If your objective is to obtain cannabis flowers, get rid of male plants as soon as possible; this allows you to avoid any possible unwanted pollination in your female plants.
• Small cycles of humidity and drought (without letting substrates dry out entirely) can increase and improve your plants’ metabolism, causing them to show their sex earlier than usual.
• You can help your plants out 10 days before flipping lights indoors with flowering stimulants such as Delta 9 by Cannabiogen or Big One by Top Crop in order to increase the formation of new flowers.
• Do not interrupt your cannabis plants’ dark cycle; one of the main causing factors of hermaphroditism in cannabis plants is interrupted darkness. This can cause small male plants to appear depending on the genetic tendency that particular strain has to become a hermaphrodite.