How To Feminize Cannabis Seeds

When it comes to cannabis plants, females are the only sex that can produce buds. Feminized cannabis seeds grow plants that are exclusively female and can almost guarantee that every plant that sprouts from their shells will flower. To determine the likelihood of the desired outcome of your marijuana plants is to feminize your marijuana seeds prior to your harvest. 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

Everything You Need to Know About Feminized Cannabis Seeds

When it comes to cannabis plants, females are the only sex that can produce buds. Feminized cannabis seeds grow plants that are exclusively female and can almost guarantee that every plant that sprouts from their shells will flower. Normally, a male cannabis plant will pollinate a female plant, and that is how seeds are produced. The resulting harvest of regular cannabis seeds will contain about half male and half female seeds. For the flower producer , this is a costly inefficiency. Roughly half of an entire grow can be tossed at harvest time if the seeds are not feminized.

Why Should You Feminize Your Seeds?

Imagine putting in the work to nurture a small 6 plant garden to find that only 3 of the plants you’ve cultivated produce buds because they’re male. If this sounds like a disappointing waste of time to you, you should feminize your seeds. Unless you are hanging on to male plants in order to develop a robust breeding program, male cannabis plants waste space and resources. Using feminized cannabis seeds removes the risk of unwanted pollination causing seedy buds or the possibility of growing flowerless male plants.

A common fear about feminized cannabis seeds is that they will produce hermaphrodites. If you purchase your seeds from a reputable seller, this fear is misplaced. Early feminizers would purposefully use female plants that were genetically likely to become intersexual. Of course, this meant that those genes were passed down to the seeds. Today, chemicals are applied to the plant without compromising the genetics of the seeds.

iStock / TRADOL LIMYINGCHAROEN

How to Feminize Cannabis Seeds

There are two ways to feminize seeds: naturally or by applying chemical substances that force a female plant to pollinate.

In nature, a severely distressed female cannabis plant will naturally become a hermaphrodite and produce pollen sacs in order to self-pollinate. This is a survival mechanism built into all female plants, but it is only triggered when the future of the plant’s lineage is compromised. Consequently, many of the resulting seeds will be naturally selected to be intersexual, and that can make for a disastrous breeding situation. A hermaphrodite can pollinate with female plants that are meant to be harvested, causing the buds to stop developing and to produce seeds.

The other reason to avoid feminizing plants the natural way is that it increases the likelihood of producing weak strains. When a female plant has been so compromised that it resorts to a sex change in order to survive, it is an indication that the plant’s genes are not strong enough to withstand the threats posed to it by its environment.

Applying colloidal silver to a female plant is the preferred method of feminizing cannabis plants. These chemicals cause the plant to develop pollen sacs without compromising the lineages’ genes.

Here’s how you can do it at home:

  1. Choose two female plants. Make sure that each plant has strong genes. One plant will be chemically treated to grow male sex organs while the other will be pollinated.
  2. Buy colloidal silver solution that has a minimum of 30 parts per million (PPM) of silver. You should be able to purchase colloidal silver anywhere that dietary supplements are sold.
  3. Spray the colloidal silver solution. On each day of the first 3 to 4 weeks of the plant’s flowering stage, directly apply the colloidal silver onto the plant’s bud sites until they are drenched. You can stop once you see that the pollen sacs have appeared and are beginning to open. Do not smoke the buds that form on this plant because they may have been coated with the colloidal silver.
  4. Collect the pollen. You will know that the pollen sacs are ready to be harvested when they are swollen and begin to split open. Simply remove the pollen sacs from the plant and let them air dry for about a week. Once they are dry, you can shake the sacs in a bag to gather the feminized pollen.
  5. Pollinate the second plant. Use the pollen you gathered to pollinate the other female plant (that plant should be about 2 to 3 weeks into its flowering stage).
  6. Harvest seeds in about six weeks. Once the calyxes on the pollinated plant are swollen and showing seeds, it is time to collect them. This takes about 6 weeks.

Cons to Feminizing

As mentioned before, old school feminizers used intersex-prone females to produce feminized seeds. Although there are better methods today, some growers continue to use this one. If you’re purchasing feminized cannabis seeds, be cautious about who you get them from. Find out how the breeder feminizes their seeds to avoid purchasing seeds that are likely to grow hermaphrodites. Even if they don’t become intersexual, there is a risk that a significant portion of the seeds will be male. You can avoid this risk altogether by feminizing the seeds yourself. We’ll explain how to do that below.

The second con to feminizing seeds only applies if you are working toward developing a breeding program. In order to grow a variety of strains, you need both male and female plants. Since male plants do not produce buds themselves, it is impossible to know what kind of genetics they can pass on without breeding them with other female plants. If you are interested in developing a specific trait profile, you should breed with several male plants until you find the desired results.

Everything You Need to Know About Feminized Cannabis Seeds was last modified: May 25th, 2021 by Dianna Benjamin

How to Feminize Seeds

It’s important to learn how to feminize seeds so you can save time on your grow. When the traditional fertilization methods are used to grow your marijuana plants, you have less control over the gender of future marijuana plants.

That is why many marijuana growers take extra steps so you receive female marijuana plants at the time of harvesting. To do it yourself, feminize seeds prior to your harvest.

What are Feminized Cannabis Seeds?

Feminized cannabis seeds produce only cannabinoid- and trichome-rich flower buds on female cannabis plants. Cannabinoids and terpenes are responsible for the potency, aroma, and flavor of cannabis.

A crop that uses high-quality feminized seeds will produce a female-only crop without the presence of male plants, which can pollinate your crop and potentially reduce your yield.

Another type of seed, a regular seed, is a result of natural pollination and breeding male and female seeds together. Cannabis growers working with regular seeds have a 50% chance of either yielding a female or male marijuana plant. Growing from regular seeds isn’t the best option if you’re looking to strictly grow cannabis buds. While male plants serve their specific purpose to pollinate females, they don’t produce the trichome covered flowers that female plants do.

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How Are Feminized Seeds Made?

Feminized cannabis seeds serve a major purpose for commercial and home growers. Feminized seeds can be made by inducing a regular female cannabis plant to grow male sex organs that contain pollen. The hermaphroditic pollen will contain only the female X chromosome and no male Y chromosomes.

When used to pollinate a female cannabis plant, the seeds produced between the two plants will inherit two X chromosomes meaning that all subsequent seeds will be feminized.

The Benefits of Growing Feminized Seeds

Growing feminized cannabis seeds has many benefits over regular seeds. For one, growers don’t have to hedge their bets hoping that the regular seeds will produce female plants. Instead of planting more regular strains than needed to get lucky and get enough females for your specific purpose, you can stick with a sure bet using feminized strains. Using feminized seeds can speed up the growing process by eliminating the need to watch out for male plants, saving you time and space.

Male plants run the risk of pollinating female plants causing them to develop hermaphroditic structures and, ultimately, lower your plants’ yield compared to a grow without male plants. Weeding out the male plants, however, takes time and energy. Male plants display their sexual organs when the photoperiod changes naturally or when indoor lighting environments change.

Growers that don’t want to spend the time monitoring the plant every day can use feminized seeds to ensure that their garden will grow flower buds. Otherwise, growers will have to keep their eyes peeled for male plants and remove them from the grow immediately.

Male vs Female Marijuana Plants

Generally speaking, there is no way that you can determine the difference between male and female marijuana seeds in the initial stages of planting. In addition, you are also not able to change the gender of your marijuana deeds. The concept of having feminized marijuana seeds is to maximize the female seeds that will be part of your marijuana crop. Why would you want female marijuana plants? Well, these are known to have a higher level of THC content. Male plants have reduced THC content and for that reason, female plants take precedence over male plants. With cannabis seed feminization, there are several pollination techniques that the marijuana grower can use for a favorable outcome.

Buying the Right Cannabis Seeds

Female marijuana seeds are sold by various companies. So, you don’t have to wait to get your own. You can use the ones available to you and by doing so, you will be sure that your outcome is a female marijuana plant with more THC content. Be careful when buying marijuana seeds from companies online. Make sure this is a reputable company known for selling and delivering the right female marijuana seeds.

Learn How To Grow Cannabis!

Some “feminized” seeds may produce hermaphrodite plants if the seeds are of low quality. High-quality feminized cannabis seeds from reputable seed banks have been bred to not display hermaphroditic characteristics under optimal growing conditions. If you’re looking for a sure thing, carefully consider your cannabis seed source.

Alternative Methods to Feminizing Weed Plants

If you are going to do the feminization of marijuana seeds yourself, then there are methods that you can use namely:

  • Colloidal Silver
  • Silver Thiosulfate Solution
  • Rodelization

Each of these methods should be successful, if used in the right way to produce female marijuana plants. Let’s quickly look at each method briefly.

Pollinating Cannabis Plants

One of the simplest ways to produce feminized cannabis seed is to pollinate your plants yourself. Some cannabis strains can produce male flowers when the colas have reached late ripeness. Side note: Ed Rosenthal, master grower and proud member of the CTU faculty, prefers to harvest plants around this time. Harvest the pollen by using a clean and small painting brush to transfer the pollen into a metal or glass container or in small amounts directly on the flowers.

Some outdoor-friendly cannabis strains may become stressed when grown in indoor environments, which can increase the chance of producing hermaphrodite flowers. Indoor growing environments can stress plants with fluctuating light cycles and heat. Stress training techniques are difficult to pull off, even for experienced cannabis growers. If you do happen to spot a hermaphrodite with pollen, collect the pollen and save it for later use when you feel comfortable using it.

Using Chemicals To Feminize Seeds

Large-scale and home growers have harnessed the power of certain chemicals that can induce male flowers in female marijuana plants. These chemicals are used to hinder ethylene production. Ethylene is a plant hormone that helps cannabis plants ripen and produce female flowers. When ethylene production is stalled, female flowers aren’t produced. Keep in mind, these chemicals must be directly applied to each branch that you want male flowers to grow.

The Silver Thiosulfate Method

The Silver Thiosulfate Solution, also known as STS, is one of the most common methods of generating female marijuana seeds. It is very effective in allowing female marijuana seeds to be available to marijuana growers. Using this method will feminize the seeds in the best way possible, making more available on the market for growers. The solution is made of a combined silver nitrate and sodium thiosulfate. The solution result is a hormonal response to stress found in the marijuana plant. Because of this, gender change is triggered.

You can do all of this yourself, but the marijuana plants have to be wisely chosen. You should only take female plants from a single cannabis strain that is almost mature. Then you would separate the plant from the bunch and spray the plant with STS. Allow it to dry and then replace it, making sure it sits alongside the other plants in the bunch.

There are over 300,000 jobs in the cannabis industry. CTU trained me for one of them!

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.