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how to feminize 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.

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.

Feminized seeds produce hermaphrodite plants:

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.

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.

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.

This is not the result of genetic or stress-induced hermaphroditism. They are genuine XX chromosome female bananas. With all the genetic information from the female and no Y chromosome, using rodelized pollen creates female-only seeds, although as with colloidal silver, an occasional male may appear.

Feminized seeds are super efficient for indoor and outdoor gardeners. Area, time, and resources aren’t being given to plants that will be thrown away two weeks after the 12-12 flip. Similarly, outdoors where a large plant can consume a lot of time and resources in upkeep prior to the autumn show of flowers, feminized plants are also a good way to reduce guerrilla crop pollinating. There’s nothing worse than bush-bashing out to a well-hidden crop only to find a rogue male or two have impregnated every female plant.

There are a number of harvesting methods employed to catch pollen.


Plants bred using feminization are homozygous. This can have two effects that can’t be assessed until the seeds are grown. Homozygosity will increase the dominant or recessive traits of the parent in the progeny, so features you don’t want and do want can be amplified. Genetics is a weird, weird thing.

  • Cover the top of the pot with plastic or card to catch pollen as it falls, or modify a plastic drink cup to shroud the plant and catch falling pollen.
  • Fix a clear plastic bag, perforated at the top for air exchange, around the whole plant.
  • An experienced eye will remove each flower pod prior to it bursting completely open to be sure of catching every spore.
  • Pollinating a female is the easy bit. Depending on how many seeds you want to make, there are a couple of methods that can be used.
  • Using a watercolour or other fine, soft brush or even a cotton bud, dip into your pollen collection and gently apply to the chosen flower. Although thousands of viable spores will be on the end of the brush, enough to pollinate a whole plant, the trichomes on the surface of the pistils will greedily glue everything you offer them. So dip into your pollen stash a few times as you dust.
  • For lots of seeds, put pollen in a bag and put over a whole branch or a whole plant, shake well, and leave for twenty four hours.
  • It is possible to pollinate different branches with different pollens and have a breeder plant that has 1, 2, or 15 different crosses on it.
  • It is also possible to self-pollinate the plant from which the male parts were created. This won’t produce as many seeds as pollinating a separate plant because less female flowers are produced and many are nonviable because of the feminization process.

Spray the plants to be feminized with colloidal silver every day, and three times a day if you can manage. Soak them well. Do this for two weeks, then leave the plants to grow as normal. Some growers report getting results after spraying for only 5–10 days.

“Applications that reduce the ethylene level in tissues or antagonise the action of ethylene causes the formation of male flowers instead of female ones” — Paraphrase, Byers et al., 1972.

The result is 50ml of pure Silver Thiosulfate, much too potent to use on your plants, so you’ll need to water it down a bit. Add your Silver Thiosulfate to 400ml of distilled water, so you’ll have around 450ml of STS. Make sure to shake quite a lot until it’s completely mixed. It’s still much too concentrated to apply straight onto your plants; take 100ml of the mixture you just made and add it to 400ml mor of distilled water. You now have 500ml of a usable STS mixture that’s ready to be used on your plants.

In order to turn a female plant male without stressing it out, all you need is some Silver Thiosulfate, also known as STS. If you apply STS to female plants it will modify their ethylene levels, which is the hormone in charge of determining the sex of certain plants. This causes female plants to change sex and turn into males without the disadvantage of male genes.

Like most living creatures, cannabis plants need a male and a female specimen to reproduce; the male pollinates the female plant which causes seeds to grow. The resulting seeds have genes from both the mother and father plants, so it has a 50% possibility of being female or male. This is why you need to find a way to get your seeds by using just female plants, completely getting rid of male genes, which only leaves the possibility for female seeds.


You can acquire silver nitrate on our webstore, although some people prefer to extract it from other products that contain it, such as Argenpal, a product used to get rid of warts – each one of these little contains a very small amount of Silver Nitrate, so it’s probably better just to buy it directly without the need to spend more money or spend forever trying to extract the Silver Nitrate from the product itself. We stock Panreac Silver Nitrate, which may be a bit more expensive but you’re guaranteed the best quality, and it saves quite a lot of time.

You generally want to use the pollen as fresh as possible on a plant that is fully ready to take it on, or else it simply might not work – it’s kind of like people, in that sense. Certain things need to be just right. To harvest large amounts of high quality seeds, you’re probably better off doing a few tests in order to find out when the right moment is. You can do this by testing it out on the same strain before going big.

STS is used by spraying it on your plants leaves, making sure that it’s entirely covered and dripping. We recommend taking the plant away from your growing area before beginning the process, or the mixture might end up getting on your other plants too. You’ll need to begin applying it 4 or 5 days after flipping the lights, right before your lights go off. This allows you to spray the plant without worrying about the light burning your plants. After 10 days, you need to respray your plants, using the same process, covering the plant in the mixture and letting it soak in in the dark.

For maximum efficiency you’ll need to use it the same day you make it. If stored in a dark, cool space it can last up to 15 days but each day it’ll be a bit less potent. If you have it for over a week and haven’t used it we recommend making another batch if you want the best possible results.