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This can be used as is, or you can cut a small intake in the bottom to improve airflow. Pollen won’t be able to escape the intake as long as the fan is moving but you might put filter paper over the intake to protect against fan failures. You can also use grommets to seal holes and run tubing into the chamber in order to water hydroponically from a reservoir outside the chamber. Otherwise you will need to remove the whole chamber to a safe location in order to water the plant or maintain a reservoir kept inside the chamber.

Marijuana Cultivation/Producing Seeds

Contents

Sooner or later every grower is going to want to produce marijuana seeds. Developing a new stable strain is beyond the scope of this discussion and requires the ability to grow hundreds or even thousands of breeding plants. However, just about any grower can manage to preserve some genetics by growing f2 seeds where they have crossed a male and female of the same strain, or can produce a simple cross which would be referred to as strain1xstrain2 for instance white widow crossed with ak-47 would be referred to as a WW x AK-47. You can produce some excellent seed and excellent marijuana this way.

To Feminise or not to Feminise Edit

There are numerous myths surrounding feminized seeds. Feminizing seeds are a bit more work than simply crossing two plants naturally. However it will save you a lot of time in the end. If you make fem seeds properly then there is no increased chance of hermaphrodites and all seeds will be female. This means no wasted time and effort growing males and it means that all your viable seeds produce useful plants. Since roughly half of normal seeds are male this effectively doubles the number of seeds you have.

Feminized seeds are bred to contain no male chromosomes, which will be able to produce the crop of resinous buds sought by most growers. For gardeners who require a quick and easy cultivation process, feminized seeds are the ideal choice. Some medicinal cannabis users may be deterred from growing their own supply because of the perceived difficulty of growing or of identifying the different genders and removing males early in the blooming period. Feminized seed-strains offer a simple solution to these issues, as there is no need to spend time in the first weeks of flowering checking for male plants.

Other times you will have no choice but to produce feminized seed because it will be a female plants genetics that you want to preserve and you won’t have any males. Perhaps you received these genetics via clone or didn’t keep males.

The new thing on the market for commercial Cannabis cultivation are auto-flowering feminized strains. By crossing of the cannabis ruderalis with Sativa and Indica strains many cultivators have created interesting hybrids which boast benefits from both sides of these families.

The first ‘auto-flowering cannabis seed’ which came on the market a few years ago was the Lowryder #1. This was a hybrid between a Cannabis ruderalis, a William’s Wonder and a Northern Lights #2. This strain was marketed by ‘The Joint Doctor’ and was honestly speaking not very impressive. The genetics of the ruderalis was still highly present which caused for a very low yield and little psychoactive effect. Not very attractive.

Auto-flowering cannabis and the easily distributed seed have opened a whole new market in the world of the online grow-shop, making it easy for home growers with shortage of space to grow rewarding cannabis plants in many different varieties. To grow plants indoors, a growing medium (e.g. soil or growing Potting soil, irrigation (water), fertilizer (nutrients), light and atmosphere need to be supplied to the plant.

Auto-flowers have been rising in popularity fast and there are now auto flower growers communities. These Web properties allow users to get information on how to grow these non photo-sensitive plants and what are the best practices when producing and germinating auto-flower seeds.

Selecting Suitable Parents Edit

There are a number of important characteristics when selecting parents. First are you making fem seeds? If you are then both parents will be female. This makes things easier. If not then the best you can do is select a male with characteristics in common with the females you hope to achieve from the seed.

Obviously potency, yield, and psychoactive effects are critical to the selection process. But some other important traits are size, odor, taste, resistance to mold and contaminants, early finishing and consistency.

Collecting and Storing Pollen Edit

In order to collect pollen you simply put down newspaper around the base of the plant. The pollen will fall from the plant onto the newspaper. You can then put this newspaper into a plastic bag and store it in the refrigerator or freeze it. Pollen will keep for a few months in the refrigerator and can be used on the next crop. Filtering the pollen through a silkscreen, drying, and freezing can extend viability for decades. At least one reader indicates success using pollen treated in this manner and stored at -30 c for 17 years. The chance of viability does decrease with time, even in the freezer, so the more fresh the pollen the better. Wrapping the pollen in a layer of aluminum foil and then a layer of plastic should help to protect it from freezer burn. Additionally, oxygen evacuation such as with a heavy gas like nitrogen or vacuum sealing should provide additional assurance of preservation.

Pollinating a Plant Edit

To pollinate a plant you can brush the pollen on a flower with a cotton swab or you can take the plastic bag, then wrap the flower inside it and shake, trapping the pollen inside for easier transportation. In this way you can selectively pollinate plants and even individual buds and branches.

Male Isolation Edit

A male plant or a plant with male flowers will pollinate your entire crop rendering it seedy. You probably don’t want THAT many seeds so how can you avoid it? Moving the male to another room might work but if that other room shares an air path via ducting or air conditioning then pollen may still find its way. One technique is to construct a male isolation chamber.

A male isolation chamber is simply a transparent container such as a large plastic storage tub turned on its side (available at your local megamart). Get a good sized PC fan that can be powered with pretty much any 12v wall adapter, by splicing together the + (yellow or red on fan, usually dotted on power adapter) and the – wires (black on fan, usually dotted power adapter) just twist with the like wire on the other device and then seal up the connection with electric tape. Then take a filtrate filter and cut out squares that fit the back of the pc fan so that the fan pulls (rather than pushes) air through the filter. Tape several layers of filter to the back of the pc fan so all the air goes through the filter. Now cut a large hole in the top of the plastic container and mount the pc fan over top of it so it pulls air out the box. You can use silicon sealant, latex, whatever you’ve got that gives a good tight seal.

This can be used as is, or you can cut a small intake in the bottom to improve airflow. Pollen won’t be able to escape the intake as long as the fan is moving but you might put filter paper over the intake to protect against fan failures. You can also use grommets to seal holes and run tubing into the chamber in order to water hydroponically from a reservoir outside the chamber. Otherwise you will need to remove the whole chamber to a safe location in order to water the plant or maintain a reservoir kept inside the chamber.

Making Feminized Seed Edit

To make feminized seed you must induce male flowers in a female plant. There is all sorts of information on the Internet about doing this with light stress (light interruptions during flowering) and other forms of stress. The best of the stress techniques is to simply keep the plant in the flowering stage well past ripeness and it will produce a flower (with seed).

Stress techniques will work but whatever genetic weakness caused the plants to produce a male flower under stress will be carried on to the seeds. This means the resulting seeds have a known tendency to produce hermaphrodites. Fortunately, environmental stress is not the only way to produce male flowers in a female plant.

The ideal way to produce feminized seed through hormonal alteration of the plant. By adding or inhibiting plant hormones you can cause the plant to produce male flowers. Because you did not select a plant that produces male flowers under stress there is no genetic predisposition to hermaphroditism in the seed vs plants bred between a male and female parent. There are actually a few ways to do this, the easiest I will list here.

Colloidal Silver (CS) Edit

This is the least expensive and most privacy conscious way to produce fem seed. CS has gotten a bad name because there is so much bad information spread around about its production and concentrations. It doesn’t help that there are those who believe in drinking low concentration colloidal silver for good health and there is information mixed in about how to produce that low concentration food grade product. Follow the information here and you will consistently produce effective CS and know how to apply it to get consistent results.

Simply construct a generator using a 9-12 v power supply (DC output, if it says AC then its no good) that can deliver at least 250ma (most wall wart type power supplies work, batteries are not recommended since their output varies over time). The supply will have a positive and negative lead, attach silver to each lead (contrary to Internet rumors, you aren’t drinking this so cheap 925(92.5%) Stirling silver is more than pure enough. You can expose the leads by clipping off the round plug at the end and splitting the wires, one will be positive and the other negative just like any old battery. Submerge both leads about 2-3 inches apart in a glass of distilled water (roughly 8 oz). Let this run for 8-24 hrs (until the liquid reads 12-15 ppm) and when you return the liquid will be a purple or silver hue and there may be some precipitate on the bottom.

This liquid is called colloidal silver. It is nothing more or less than fine particles of silver suspended in water so it is a completely natural solution and is safe to handle without any special precautions. The silver inhibits female flowering hormones in cannabis and so the result is that male flowering hormone dominates and male flowers are produced.

To use the silver, spray on a plant or branch three days prior to switching the lights to 12/12 and continue spraying every three days until you see the first male flowers. Repeated applications after the first flowers appear may result in more male flowers and therefore more pollen. As the plant matures it will produce pollen that can be collected and used to pollinate any female flower (including flowers on the same plant).

Silver Thiosulfate (STS) Edit

Silver Thiosulfate is a substance that has similar principle, application and results of CS, but is more difficult to make. STS is more difficult to acquire, but it can still be obtained directly from a chemical supply company. STS is not an expensive or controlled substance.

Gibberellic Acid (GA3) Edit

This is probably the most popular way to produce feminized seed, but at the same time the least effective. GA3 is a plant hormone that also causes the plant to stretch uncontrollably. It can be purchased readily in powdered form, a quick search reveals numerous sources on e-bay for as little as $15. Simply add to water to reach 100ppm concentration and spray the plant daily for 10 days during flowering and male flowers will be produced.

Make cannabis seeds
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.

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!

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).

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).

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.