How To Feminize Cannabis Seeds

Feminized seeds have been increasingly rising in demand ever since medical cannabis became legal, but how do we make feminized seeds? Feminized marijuana seeds can streamline the growing process and ensure that cannabis cultivators get the most out of their hard work. Read all about the process here. At this point in time, we all know what feminised seeds are, although even today there is some confusion regarding the most common methods to produce

3 Best Ways to Feminize Cannabis Seeds

Most people are already aware that cannabis buds we use today come only from female plants.

Male plants pollinate female plants, which produce seeds upon pollination.

Just like children, some seeds end up being female and some male. That’s just how nature works.

A male plant can pollinate a whole room of female plants. Even if there were 50 plants in that area, all the male plant requires is a bit of wind, and each female plant will end up being fertilized.

Getting only feminized cannabis seeds is not an impossible task, you just have to work around the rules set up by nature.

Why are seeds feminized?

Cannabis growers need seeds that are guaranteed to grow into female plants, in order to avoid pollination of the entire crop.

No one wants seeds in their weed and because of this issue we require feminized seeds.

When you’re certain that all your seeds are feminized, you can grow big crops knowing that your plants are safe from pollination by a male plant.

Breeders and seed producers also want feminized seeds for business purposes, as they’re in very high demand in places where growing weed is legal.

As cannabis becomes legal in more places throughout the world, feminized seeds are the first small-time thing new growers will start looking for.

Reliably producing female plants is of great value in this industry, because only female plants produce flowers with medicinal value.

How to feminize seeds?

When breeding cannabis, growers will intentionally pollinate their females in order to get certain traits in the offspring.

How to Start Your Own Marijuana Seeds Breeding Program?

However, sometimes the breeder isn’t looking to cross two strains in hopes of getting a specific trait.

Once the breeder stabilizes a certain trait, he’ll look to mass produce the offspring with precisely those traits. He may do so by feminizing seeds that the “mother plant” produces.

In the wild and without any human tampering, cannabis plants produce mostly female seeds when they “perceive” that they’re approaching the end of their lifetime.

Feminization is essentially a process of pushing the plant to produce as many female seeds as possible, by making it “think” that it’s approaching its last days.

In order to survive and spread its genetic material as much as possible, plants will mostly make female seeds, and a very small percentage of male seeds, because a small number of males plants can pollinate a colossal number of female plants.

This is why the process of pressuring the plant to produce female seeds en-masse is called feminization.

There are several ways to perform seed feminization. Each one is different, although they all boil down to the same thing — getting female seeds.

Some methods are more efficient than others, which is why they are preferred by numerous producers and growers.

Feminizing seeds with colloidal silver

Colloidal silver is a substance made from microscopic particles of silver, which are suspended in liquid. Particles of silver are less than 100nm (nanometers) in size, and completely invisible to the naked eye.

You can get bottled colloidal silver on Amazon, or you can make it yourself, which is also relatively simple.

If you’re going to use it only a few times don’t bother making it, just order a couple of bottles.

Colloidal silver works by inhibiting female flowering hormones in cannabis. The result of this is that the male hormones dominate, and thus male flowers are produced.

By doing so, you turn your healthy female plants into males. Afterwards, you use the pollen that came off that plant to pollinate the other plants.

After you pollinate the other female plants, they will produce feminized seeds. This technique is reliant and yields female seeds in huge numbers.

Cannabis is known to yield hundreds (sometimes even thousands) of seeds after being pollinated. The colloidal silver method guarantees that you consistently get feminized seeds.

Here’s how to use it:

Spray colloidal silver on the branches every three days prior to switching the lights to 12/12 and continue spraying it until you start seeing first male flowers.

The more you use it, the more pollen sacks you will get. As the plant matures it will produce pollen that should be collected and used to pollinate other female flowers.

Collect the new seeds and plant them to get the next generation of the same plant.

Feminizing with Gibberellic acid

Feminizing with Gibberellic acid is even easier than with colloidal silver.

Gibberellic acid can also be bought in stores, and it’s mostly available in powder-form.

Gibberellic acid isn’t expensive at all, you can order it online or buy an entire box for as low as $15 bucks.

Mix the gibberellic acid with water so it reaches around 100 ppm (parts per million, the instructions on the packaging will let you know what’s what), and spray that water/acid mix on the plant once a day, for 10 consecutive days during the flowering phase, and male flowers will be produced.

After that apply the pollen from the “gibberellic acid” male flowers on other healthy female plants.

Those plants will yield feminized seeds after being pollinated.

Feminizing with the rodelization method

The rodelization method is by far the slowest, the least efficient, and the least guaranteed to work out of these 3 methods.

Rodelization entails not harvesting flowers after they’ve bloomed, but rather forcing the plant to turn male, in order to preserve itself.

After the plant has flowered, you need to leave it like that for another few weeks. The plant will then stress itself and grow a couple male flowers, in an attempt to pollinate itself once more.

If your plant succeeds, you’ll need to wait an additional few weeks to get decent seeds that are ready for sowing. Keep in mind that this method is not as reliable as the other two, and yields a smaller number of seeds.

This is “nature’s way of feminizing seeds”, although like everything else with nature, it takes a lot of time. A lot more time compared to the gibberellic acid and colloidal silver.

All these factors make rodelization the most natural, but for growers by far the worst possible feminization method.

What Are Feminized Cannabis Seeds?

This article is sponsored by Kannabia Seed Company, an award-winning cannabis seed company headquartered in Spain. Using only the highest quality genetics on the market, their grower-oriented approach has made cannabis cultivation simple and satisfying for growers of all skill levels for years.

Anyone who’s ever savored a joint owes their enjoyment to the fruits of the cannabis plant, but moreover, to the female of the species. That’s because only female cannabis plants produce the cannabinoid-rich flowers that deliver the flavors and effects consumers look for.

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This is why many North American growers are turning to feminized seeds—cannabis seeds that carry only female genetics, and can be relied on to produce only female plants. By creatively applying technologies to seed feminization, modern breeders like Kannabia can ensure female genetics in seeds with a nearly 100% success rate.

Male vs. Female Cannabis Plants

A bud of Diesel Glue grown from Kannabia’s feminized seeds. (Courtesy of Kannabia)

Cannabis plants that are pollinated naturally or with traditional breeding techniques can produce both male or female seeds. These are known as regular seeds and, as in most species, they occur with about an even split between the two sexes. That means cannabis cultivators starting with standard seeds have about a 50% chance of yielding a female plant from each one.

As a result, growing cannabis from regular seeds isn’t very efficient—it’s akin to running a bakery that has to throw out every second loaf of bread. Growers working from regular seeds have to account for the fact that roughly half of their plants could be males. While those plants are of some value to breeders, folks growing for flower won’t find much to like in them, and too many male plants can spoil a grow.

Traditionally, the solution to this has been an inelegant one, with many cultivators planting at least twice as many seeds as they hope to harvest with the assumption that about half of them will be useless. However big a harvest you’re looking for, using regular seeds means you’ll have to plant twice that many seeds.

Why Grow From Feminized Cannabis Seeds?

Cultivators depend on feminized seeds for efficient growing cycles. (Courtesy of Mr. Sticky Farm)

There are numerous advantages for growers who start their garden using feminized seeds. By removing the guesswork of germinating regular seeds, feminized seeds streamline the growing process, saving space and time.

That efficiency is key for medical cannabis patients and hobby growers. Since most cannabis regulations limit plant counts, growers cultivating a small crop of cannabis for personal use want to ensure they’re getting the most out of their grow.

Male plants don’t just take up space in a garden, either. They can also sap time and resources from growers. When male and female plants are both present, growers need to cultivate both until their sexes are clear. While some strains will show early signs of their sex before flowering begins, most cannabis plants don’t begin to express their sex until they start to mature past the vegetative stage.

This change occurs when the photoperiod, or amount of light and dark that the plant receives, changes to 12 hours of light and 12 hours of dark. In outdoor gardens this change can happen naturally with the seasons or, in more controlled environments like indoor gardens, by human intervention using light timers.

Once those plants are old enough, growers have to go to the trouble of actually determining their sex, monitoring each individual plant to ensure any males are removed before they can pollinate their female counterparts.

Growers can avoid spending weeks nurturing plants with only a 50% chance of expressing as female and maximize the space and plant count in their gardens by using feminized seeds from suppliers like Kannabia. These specially-treated seeds increase the probability of producing a female plant to 99%.

How Are Cannabis Seeds Feminized?

Treating cannabis seeds with a silver thiosulphate solution can ensure the resulting plants are females. (Courtesy of Kannabia)

There are a few techniques that can produce reliably feminized seeds. One classic method is stressing out a healthy female plant by interrupting its light cycle during flowering. While that works to an extent, the more common and controlled method is to spray down female plants with a collodial silver or silver thiosulphate solution. This method makes it possible to control the sex of a plant without any genetic tinkering or modification.

Both substances are a blend of water and fine silver particles, and they work in largely the same fashion. The silver solution impedes the production of ethylene, a hormone involved in flowering. The result is a female plant, but one that produces male flowers with pollen sacs. Since those pollen sacs develop on a plant with only female genetics, female genetics are all they carry. When those flowers pollinate another female plant (one untreated by silver solutions), the resulting seeds are nearly certain to be female.

Treating plants with a silver thiosulphate solution results in seeds that will produce feminized plants nearly 100% of the time, and Kannabia’s breeders have found this method to be the most effective way to maintain the stability of the seeds and future feminized plants.

Feminized Varieties to Try in Your Garden

Using feminized seeds can make it easier for home growers to cultivate strains like Russian Doll. (Courtesy of Kannabia)

Growing cannabis in your home is legal in an increasing number of states and provinces throughout the United States and Canada. To make starting a home garden easy, growers can start with feminized seeds for many popular strains from providers like Kannabia.

“In our search to find new genetics, Kannabia paired us with their feminized Russian Doll seeds,” say growers at Canada’s BlueSky Organics. “Every seed germinated, and now that we are in the late vegetative stage, these plants have an extremely hardy trunk preparing themselves for some massive buds.”

If you have more questions about strains or seeds, keep digging through Leafly’s resources. And to learn more about the variety of feminized seeds available to you, visit Kannabia’s website to see its full line of feminized genetics, including strains like Diesel Glue and the award-winning Mataro Blue.

Promotions are offered solely by Kannabia Seed Company. Terms and conditions may apply—contact Kannabia for full details.

How to make feminised cannabis seeds

Until the 1990s, any cannabis cultivator was aware that, at some point, they had to separate the male and female plants if they didn’t want the first ones to pollinate the latter, which results in plants completely full of seeds. However, those were the days when pioneering seed banks like Dutch Passion were revolutionizing the cannabis scene with the birth of the first feminized cannabis strains, or in other words, seeds that only develop into female plants. At the beginning of the 20th century, many seeds banks were offering this type of seeds, feminized versions of classics strains that had been cultivated during many years as regular plants.

We are sure that by now you’d probably have grown some feminized seeds, maybe even though you are a purist and the fiercest defender of regular seeds. But. do you know where feminized seeds come from? Are you familiar with the processes used by both breeders and growers to obtain them? In this article we explain everything!

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Feminized cannabis seeds quality control

Advantages of growing feminised seeds

Indeed, the advent of feminized seeds brought about a genuine revolution within the cannabis sector. Growers were now sure that all their plants would be females, without the need to differentiate between male and female plants or having to remove the males before they could ruin the crops, which offers a number of benefits of significant importance:

  • Space and resources saving: no more growing plants which eventually will be removed for being males.
  • Reliability: it’s not that most plants are female, or that they are genetically more likely to produce female plants. The plants grown from feminized seeds have only female chromosomes (XX), therefore this method is 99% reliable.
  • Sinsemilla plants: by not having males in the grow room, your female plants won’t be pollinated, so they won’t produce any seeds during the flowering period (something that every cultivator wants, unless they want to obtain seeds)

These advantages were of great interest for the growers, and soon feminised seeds accounted for a large portion of the seeds available in the market. In addition, being able to use only female plants (generally known and selected clones) to produce seeds had another great advantage for seed producers and breeders of new varieties: they no longer need to keep males in their gene pools! And not only that. from that moment on, any female plant they could get their hands on could be used as a male to pollinate other plants, thus exponentially increasing the possibilities of creating new crosses.

Outstanding Orange Candy feminised from Philosopher Seeds

It is not surprising, therefore, that at present, feminized seeds represent virtually all the seeds in the market, since they offer a number of significant advantages for both professional and home growers and breeders, for photoperiod and autoflowering plants. The main disadvantage of this method is a well known and hotly debated issue: the growers who buy this type of seeds cannot produce their own seeds in the absence of male plants, so the only way they can manage it it’s using the same process to obtain this type of seeds. But. what are these processes and what are they based on?

Female crosses: feminised cannabis seeds are born

As we’ve already mentioned, feminized seeds are the result of a process that reverses the sex of a female plant, that is, she is forced to produce male flowers. This way, and once into flowering, the female chosen will start to develop what we know as male flowers (stamens and anthers), which, just like male plants, will release the pollen that will pollinate the female plants. What is then the difference between a male plant and a reverted female plant?

The sex of cannabis plants is determined in the same way as ours, through the so-called sex chromosomes or genosomes. Male plants have a couple of different sex chromosomes called “XY” or heterogametic, while female plants have two chromosomes called “XX” or homogametic. When crossing a male (XY) with a female (XX), we will obtain around half of the plants of each type in their offspring. In other words, when a breeder uses a male and a female plant, the seeds produced by them will be approximately 50% males and 50% females.

After this explanation, many of you will have already figured out that if we cross two female plants (reversing the sex of one of them to force it to produce pollen), the result will be seeds that will produce female plants, as there are only female sex chromosomes in the equation. If crossing XY with XX produced 50% of each class (male and female), crossing XX with XX will produce plants that only exhibit chromosomes XX, that is to say, female plants. No matter how many times we “transform” a female plant into a male plant, we won´t be changing their genetic composition, which will still be female or XX. This way, the pollen produced by this plant will pass down female sex chromosomes exclusively.

Feminised seeds grown indoors, 100% female plants

As you can see, and although we normally use the expression “reversing the plant sex“, that is not exactly what is done, because the sex chromosomes of the female plant (XX) have not changed, even if we managed to produce male flowers. This “sex change” of female plants can be achieved in a number of ways, but usually with the same goal: to reduce the level of ethylene in plant tissues and/or inhibit the ethylene action, which makes the plant develop male flowers on entering the flowering period, as if it were a male from regular seeds. This is because ethylene is a natural regulator of the sex expression in plants!

Let’s see now the most popular ways to reverse the sex of a female plant in order to produce feminized seeds.

Methods used to produce feminized cannabis seeds

There are several ways to secure that a female plant produces pollen, and almost all of them require some type of chemical that is often sprayed on the plant. Once sprinkled with the chosen product and under a flowering photoperiod, the plant will flower normally, but as a male instead of female, producing ‘feminized’ pollen (which only contains chromosomes XX) that can be used to pollinate other females in order to produce seeds. These are some of the most commonly used techniques:

Stress or rodelization

One of the first methods used to obtain seeds that produce female plants was stress or rodelization. There are several ways to stress the cannabis plants to make sure they develop male flowers, such as through temperature, nutrition, photoperiod, and pH. However, supporters of this technique often prefer something as simple as delaying the harvest 2-3 weeks in order to force the plants to develop a few male flowers without stressing them as much as with any of the other methods we have mentioned.

Although this action will produce far less pollen than other techniques like STS, it will be enough to obtain a handful of seeds for the domestic growers to try to create their own feminized crosses. Also, the great advantage of this technique is that is 100% natural, and it doesn´t use any chemicals. It is an excellent alternative for anyone who just wants a few seeds and wishes to keep it simple without any formulas or laboratory products. However, bear in mind that this is the only method listed in this post that may produce some plants with hermaphroditic traits.

Male flower produced by rodelization

STS or silver thiosulfate solution

Without any doubt, one of the most commonly used methods for both producers and seed banks. This is a solution made of distilled water, silver nitrate and sodium thiosulphate (sometimes called sodium hyposulphite) that, after being sprayed on the female plants, inhibits their ethylene action resulting in the formation of male flowers once flowering has been induced. STS is relatively easy to prepare, although its lifespan after combining the two components is quite limited, barely a few days as long as it´s well preserved (in a dark and cool place).

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It is important to mention that you must not consume any part of the plants sprayed with this type of product, although that would be weird, as the plants have “become” males and won´t produce any buds. Nevertheless, you shouldn’t use the reverted plants to make resin extracts; the best thing is to discard them after harvesting the pollen. Both components, sodium thiosulphate and silver nitrate, are also used for photo-development.

Colloidal silver

This is another way to revert the sex of the plants, but this time using a solution made of 30ppm colloidal silver (that you can easily find in many pharmacies and also online) and distilled water. The solution must be applied for a few days until the plant starts producing male flowers, something that it´s not necessary with STS, where in most cases one single application is enough.

Colloidal silver is formed by electrically charged silver nanoparticles and has antibacterial and antifungal properties. This product was introduced in the market in 1980 for therapeutic use. However, as with STS, you should get rid of the sprayed plants once their pollen is harvested, as colloidal silver is absorbed systemically by the plant and remains in its tissues.

This sativa plant treated with STS started flowering as a female but soon developed male flowers

Silver nitrate

This is a method researched by Mohan Ram, who also conducted extensive investigations on plant sex reversal with STS. According to his findings, sodium thiosulphate (STS) is more effective in producing male flowers and viable pollen in female plants. Probably because of this, silver nitrate is mixed with sodium thiosulphate, instead of using it in isolation.

Gibberellic acid

Gibberellins are plant hormones that help regulate various processes related to the development of the plants. There are several types of gibberellins available in the market, although the most common and effective is gibberellic acid or GA3 (Gibberellin GA3). This product is used in a very similar way to colloidal silver, sprayed on the plants during several days before switching the photoperiod over to flowering.

It is worth stating that one of the side effects of gibberellic acid is a significant stretching of the treated parts of the plant, so don’t be surprised if this happens to your plants! The recommended dose to achieve the best results is approximately 100ppm.

Urban legends and lies about feminized seeds

Despite the fact that, after two decades of cannabis cultivation, many of the false myths surrounding feminized seeds have been debunked, from time to time we still hear some arguments like the ones shown below. As is often the case, many of these stories are spread by people who have never grown this type of seeds or have none or very limited experience with them. Ignorance is always a bad thing, and that’s why we want to emphasize several points in relation to feminized seeds and the myths that often go with them; myths such as the following:

Feminized seeds produce hermaphrodite plants:

The problem with monoecious hermaphrodite plants has more to do with the parents used (and if they exhibit any hermaphrodite trait) rather than with the type of seeds produced. If to create a feminized seed you use a female plant with a tendency to produce male flowers, part of its offspring will likely inherit that characteristic, whether the said female plant is used as a pollen donor (after reversing its sex) or as a recipient of pollen (letting it flowering as usual). Yet the same thing happens when producing regular seeds: if the male or female parents are not stable in this respect, neither will be their offspring (or at least part of it).

Marijuana and hermaphroditism

Many growers have been surprised by the presence of hermaphrodite plants in their marijuana crops. In this post we will tell you how to detect them and how to proceed if you find a hermaphrodite cannabis plant in your growing space. We will also discuss the causes of this hermaphroditism.

Feminized seeds produce mutant plants:

Nothing could be further from the truth. It is true that sometimes some plants develop weird traits or mutations, although this also happens with regular seeds. Unfortunately, there seems to be not enough studies comparing the ratio of specimens with mutations of one or other type of seeds; however, given the millions of feminized seeds that have been germinated in the last 20 years, if mutations would pose a problem, the quantity of feminized seeds sold would certainly not be so high, and this would be a “public security” issue within the cannabis sector, both for the growers and the producers of the seeds.

Feminized seeds have chemicals:

This is another lie that some people believe. As it’s been mentioned before, a female plant is sprayed with some chemicals in order to inhibit its ethylene action. After a few weeks of this and once in the flowering period, the plant will produce male flowers and pollen, which will be harvested to pollinate the female plants designated to produce seeds. Once the seeds are formed, they are collected and packed immediately, so they don’t come into contact with any chemicals or the plants that produce seeds, nor, of course, with the seeds themselves. Also, to produce cannabis seeds, you normally need two separated indoor cultivation areas, one for the reverted plants (treated females) and the other for the females to be fertilized to produce the seeds, so the latter can’t get “contaminated” with any chemicals.

Feminized seeds are GMOs:

Once again, this is a false statement. We have already pointed out that by using these sex reversal techniques we inhibit the ethylene action in the female plant, and under no circumstances the seeds (or plants) are genetically modified. The sex chromosomes of the female plant converted into a male plant are still female (XX), nothing has changed at a genetic level.

We hope you found this article interesting; even today, many people are still unaware of the intriguing process behind this type of cannabis seeds. Do not hesitate to leave your comments; we will be delighted to answer them.

  • Marijuana Botany, Robert C. Clarke
  • The Cannabis breeder’s Bible, Greg Green
  • The Cannabis grow Bible, Greg Green
  • Breed your own vegetable varieties, Carol Deppe
  • Induction of Fertile Male Flowers in Genetically Female Cannabis sativa Plants by Silver Nitrate and Silver Thiosulphate Anionic Complex, Mohan Ram, Sett R.

The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.