Register ICMag Forum Menu Features Search Today's Posts Mark Forums Read
You are viewing our:
Forums > Marijuana Growing > Marijuana Strains and Breeding > Breeder's Laboratory > Feminizing seeds.

Thread Title Search
Post Reply
Feminizing seeds. Thread Tools Search this Thread
Old 01-02-2011, 01:32 PM #1
I'm always here when I'm not someplace else

Stress_test's Avatar

Join Date: Oct 2010
Posts: 2,527
Stress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of lightStress_test is a glorious beacon of light
Post Feminizing seeds.

Okay I was asked about using STS or Colloital Silver to create feminized seeds. I know that I have read it here and many people on ICMag know what the process involves. However alot of people have never heard of it or other methods/techniques to create feminized seeds. So I thought a thread that combines the different methods/techniques in one easy to locate thread would be helpful.

When growing regular cannabis seeds, the resulting plants end up being about 50% male and 50% female. This can be a big disadvantage to the grower because male plants do not produce usable buds and generally must be discarded. However, if you create feminized seeds, then all the resulting plants will be female.

While there are a few different ways to create feminized cannabis seeds, for some people making your own feminized seeds may be impractical.

There are two main methods to create feminized cannabis seeds, genetically induced using the STS or CS (colloidal silver) methods or using the Rodelization method.


How it Works:

Probably the most common method used to create feminized seeds is to take a known female cannabis plant and force her to grow male pollen sacs and produce pollen. You can then take this all-female pollen and use it to fertilize other females. Because all the genetic material comes from females, you will end up with seeds that are generally about 99% female. Any male plants that do result when growing feminized seeds are probably genetic females that are growing with male characteristics.

There are several processes by which female plants will grow male characteristics. Some female plants will start growing male organs if they are left in flowering for too long, as a last ditch attempt to pollinate themselves since they were not pollinated by "true" male plants. Some female plants will also show male characteristics as a result of heat and light stress. But for the grower, the easiest, most reliable and most convenient methods to get a female cannabis plant to make pollen is to treat her with a solution known as colloidal silver, or STS.


Below I explain how to make feminized seeds using both STS, CS methods, then I'll briefly explain the all-natural rodelization method, which is an all natural though less reliable way to get feminized seeds.



I have had this text file on my hard drive and various backups for around 10 years and honestly don't remember where I got it originally. I suspect that either I copied it off of the internet or it was passed down from another grower. Now I am glad to pass it on again with my own modifications and tweaks.

The following is a safe, inexpensive, and successful method for reversing the sex of female cannabis plants. Individual plant responses may vary based upon strain, but I can verify that this process is fully effective in stimulating profuse staminate flower production.

This process can be used to:
A: create new feminized seeds from solitary prize mothers that you currently have
B: create interesting feminized-seed hybrids from different prize strains that you currently have
C: create feminized seeds for optimum outdoor use
D: accelerate the "interview" phase of cultivation, in searching for interesting new clone-mothers
E: reduce total plant numbers- great for medical users with severe plant number restrictions
F: increase variety, by helping to create stable feminized seedlines to be used as an alternative to clones

At the bottom of this post are some specific details about the chemicals used, their safety, their cost, and where to get them.

It is important to educate yourself about cannabis breeding theory and technique prior to using a method like this one.

It is also important to use basic safety precautions when mixing and handling these chemicals, so read the safety data links provided. The risk is similar to mixing and handling chemical fertilizers, and similar handling procedures are sufficient.

Remember: nothing will ever replace good genetics, and some of your bounty should always go back towards the professional cannabis breeders out there... the ones who have worked for many generations to come up with their true-breeding F1 masterpieces. Support professional breeders by buying their seeds.


Preparation of STS:
First, a stock solution is made. It consists of two parts (A and B) that are initially mixed separately, then blended together. Part A is ALWAYS mixed into part B while stirring rapidly. Use distilled water; tap water may cause precipitates to form.

Wear gloves while mixing and using these chemicals, and mix and use in a properly ventilated area. A mask will prevent the breathing of any dust, which is caustic. STS is colorless and odorless, and poses minimal health risks if used as described here. (See material safety data sheet links below). Note that silver nitrate and STS can cause brown stains upon drying, so spray over newspaper and avoid spilling.

Part A: .5 gram silver nitrate stirred into 500ml distilled water
Part B: 2.5 grams sodium thiosulfate (anhydrous) stirred into 500ml distilled water

The silver nitrate dissolves within 15 seconds. The sodium thiosulfate takes 30-45 seconds to dissolve.

The silver nitrate solution (A) is then mixed into the sodium thiosulfate solution (B) while stirring rapidly. The resulting blend is stock silver thiosulfate solution (STS).

This stock solution is then diluted at a ratio of 1:9 to make a working solution. For example, 100ml of stock STS is added to 900ml of distilled water. This is then sprayed on select female plants.

Both the stock STS and the working solution should be refrigerated after use, as well as the powdered chemicals, to avoid activity loss. Excess working solution can be safely poured down the drain after use (with ample running water) with negligible environmental impact. It's pretty cheap.

Each liter of stock STS will make ten 1-liter batches of working solution of STS. With the minimum amount of base chemicals ordered from Photographer's Formulary (see link below), this means that each 1-liter bottle of working solution STS costs less than 9 cents, and can treat 15-20 mid-sized plants. That's 200 1-liter batches of STS for $18. Note that the distilled water costs far more than the chemicals.


The STS working solution is sprayed on select female plants until runoff. Do the spraying over newspaper in a separate area from the flower room. You probably won't smell anything, but ventilate anyway. You now have what I call a "F>M plant"; a female plant that will produce male flowers.

I have discovered that using a stronger concentration of STS does not make a plant more likely to produce pollen. It just burns/stresses the plant. What DOES make a plant much more likely to complete it's mission and make pollen is a second spraying at the end of week 2.

My conclusion is that STS in any concentration is only effective at inhibiting ethylene for about 3 weeks; at that point the plant's natural female metabolism begins to take back control, and even a plant that is covered with male blooms doesn't always finish the journey to manhood and produce pollen. A second spraying allows inhibition to last through week 6, which is more than enough time to release pollen.

After the F>M plant dries move it into 12/12 immediately. This is usually done three to four weeks prior to the date that the target (to be pollinated) plants will be ready to pollinate. Response times may vary slightly depending upon the strain. More specific times can be determined by trial with your own individual strains. In my application it takes around 26 days for the first pollen. 30-35 days seems optimum for planning purposes.

So, assuming that a target plant needs 3-4 weeks to produce fully mature seeds, a strain that takes 8 weeks to mature should be moved into flower at about the same time as the female>male plant. A target plant that finishes flowering in 6 weeks needs to be moved into flower later (10 days or so) so that it doesn't finish before the seeds can fully mature.

A seeded individual branch can be left to mature on a plant for a bit longer, while harvesting the other seedless buds if they finish first. Just leave enough leaves on the plant for it to stay healthy.


Within days I noticed a yellowing of the leaves on the F>M plants. This effect persisted for two weeks or so; after this they became green again, except for a few of the larger fans. The plants otherwise seem healthy. No burning was observed. Growth stopped dead for the first ten days, and then resumed slowly. No stretch was ever seen. After two weeks the F>M plants were obviously forming male flower clusters. Not just a few clusters of balls, but complete male flower tops. One plant still formed some pistillate flowers, but overall it was predominantly male.

It is strange indeed to see an old girlfriend that you know like the back of your hand go through a sex change. I'll admit that things were awkward between us at first.

When the F>M plants look like they may soon open and release pollen, ( 3-1/2 to 4 weeks) move them from the main flower room into another unventilated room or closet with lighting on a 12/12 timer. Don't worry too much about watts per square foot; it will only be temporary.

When the pollen flies, move your target plants into the closet and pollinate.

A more controlled approach is to isolate the F>M plants in a third remote closet (no light is necessary in this one, as they are releasing pollen now and are nearly finished anyway). In this remote other closet the pollen is very carefully collected in a plastic produce bag or newspaper sleeve and then brought back to the lighted closet, where the target plants are now located. If this is done, be careful to not mix pollen types by letting the F>Ms dust each other. Avoid movement, or use yet another closet.

Take special care to not let pollen gather on the outside of this bag- a static charge is sometimes present. Drop small open clusters of blooms inside and then close the bag at the mouth and shake. Important: next, step outside and slowly release the excess air from the bag, collapsing it completely, so that pollen doesn't get released accidentally. Points downwind; don’t let it get on your hands or clothes. I always shower and change clothes at this point...

This collapsed pollinated bag is now very carefully slipped over only one branch and is then tied off tightly at the mouth around the branch stem with a twist tie or tape, sealing the pollen inside. Let the bag inflate slightly with air again before sealing it off, so the branch can breathe. This technique keeps the entire plant from seeding. Agitate the bag a bit after tying it off to distribute the pollen. Don't forget to label the branch so you know which seeds are which. Other branches on this same plant can be hit with different pollen sources.

If no lighted closet is available, the plant can be moved back into the main room, but- be very careful: pollen is sneaky. After 4-5 days, the bag is gently removed and the plant completes its flowering cycle.

Yet another method that has worked well for me. I position the target plants in a non-ventilated lighted closet, and then I collect pollen on a piece of mirror or glass. This is then carefully applied to the pistils of one pre-labeled branch by using a very fine watercolor paintbrush. Care is taken to not agitate the branch or the pollen. No sneezing. The plant needs to be in place first; moving it after pollination can shake pollen free and blow this technique.

Regardless of technique, at completion you will have feminized seeds. Let them dry for 2-4 weeks.


About the chemicals:
Silver nitrate is a white crystalline light-sensitive chemical that is commonly used in photography. It is also used in babies' eyes at birth to prevent blindness. It can cause mild skin irritation, and it stains brown. Avoid breathing. I didn't notice any smell or fumes, but ventilation is recommended. Be sure to wash the spray bottle well before you use it elsewhere; better yet: devote a bottle to STS use. A half gram is a surprisingly small amount; it would fit inside a gel capsule.

Where to get the chemicals:

silver nitrate: 10 grams: $10
sodium thiosulfate (anhydrous): 100 grams: $3.95
Postage runs around $4. Fast service. [verified!]

Have fun experimenting with this technique. Use it responsibly.


For what it's worth, here is some information I found about sex-reversal in cannabis. This was printed in the memoirs of H.Y. Mohan Ram, found as a .pdf file which I discovered years ago and surprisingly it is still there.
Here is a link to the .pdf file:

He states that fertile male flowers can be induced in female cannabis plants using:
gibberellins (GAs) and anti-ethylene agents such as:
silver nitrate (AgNO3)
silver thiosulphate anionic complex (STS)
aminoethoxyvinyl glycene (AVG)
and cobalt chloride (CoCl2).

As this was an aside mentioned in the larger context of Dr. Ram's life work, he does not go into detail regarding the methods of application of these chemicals to achieve the sex reversal. However the papers cited below do cover more details.

Mohan Ram H Y and Juiswal VS. 1972. Induction of male flowers on female plants of Cannabis sativa by gibberellins and its inhibition by abscisic acid. Plants, 105:263-266.

Mohan Ram H Y and Sett R. 1981. Modification of growth and sex expression in Cannabis sativa by aminoethoxyvinylglycine and ethephon. Z. Pflanzenphysiol., 105:165-172.

Mohan Ram H Y and Sett R. 1982. Induction of fertile male flowers in genetically female Cannabis sativa plants by silver nitrate and silver thiosulphate anionic complex. Theor. Appl. Genet., 62:369-375


Using Colloidal Silver to create feminized seeds:


* You're able to produce feminized seeds using any two female cannabis plants (even clone-only strains!)
* You can produce seeds consistently
* You can control how many seeds produced
* Easy to make hundreds of feminized seeds if needed
* You can pollenate plants with various different male pollen


* You will need to find a source of colloidal silver. Your main options are: buying colloidal silver directly, buying a colloidal silver generator, or making your own simple colloidal silver generator yourself (instructions below)
* It is not safe to directly use/consume any cannabis which has come into contact with colloidal silver, though any seeds produced by a treated plant's pollen are 100% safe.


When a female cannabis plant is treated with a solution of tiny silver particles suspended in distilled water, the plant will start to exhibit male characteristics. This solution of silver in water is called colloidal silver and can be purchased from a pharmacy/online or easily made at home. Some people drink colloidal silver for its health benefits and others use it occasionally on plants to help control bacteria, insect, and fungus growth on the leaves.

However, if you thoroughly mist a female cannabis plant with colloidal silver every day for 10-14 days around the same time that she enters the flowering stage, the concentration of silver ions in the water actually act as an ethylene inhibitor/antagonist on the plant, which forces the plant to create male pollen sacs instead of female buds. The safest way to ensure that your plants will actually turn into males is to keep misting the plants until you see the beginning of male pollen sacs forming. If growing indoors, you start misting the cannabis with colloidal silver when your first change the lights to 12-12, and keep misting her daily until the treated parts start showing male pollen sacs.

You need to let the sacs swell like a big empty balloon. You will be able to tell when they are about to open because the leaf section protecting the pollen starts to crack. At this point, simply take the pollen sacs off and place them in a cool dry place for a week and let them start to dry. The pollen will come out if you shake them about a little, or you can also cut open the sacs to get to the pollen inside. Use this pollen to pollinate female plants and you will get all-female seeds that are a mix of both their mothers.

This method is great because it will force almost any cannabis plant to show male characteristics. Unlike the rodelization method described below, you are not selecting for plants that show hermaphrodite traits. The genes of the plant are completely unaffected. This method will also produce a lot of pollen consistently compared to the rodelization method.

The one downside to this method is that it is not safe to use any cannabis that has come into direct contact with colloidal silver. You should therefore destroy the plant after the pollen has been collected. You will also want to ensure that you clean off any remaining traces of silver off your equipment in case you accidentally contaminate another cannabis plant with silver.

Here are the main things to keep in mind when using colloidal silver:

* Make sure you spray the cannabis with a strong enough colloidal silver solution (at least 30 PPM of silver)
* Spray the cannabis thoroughly to almost drench all the parts you want to turn into pollen sacs
* Spray the cannabis regularly, at least once a day for 10-14 days, starting when you change the lights to 12-12
* Spray the cannabis with colloidal silver every day until you see signs of male pollen sacs forming. Some hardy strains may need over 2-3 weeks spraying before they 'turn'.

Where to Get Colloidal Silver:

Colloidal Silver is created by submersing two pieces of pure silver in distilled water, and then running a small DC electric current between the two pieces of silver. The electric current will cause silver ions to be deposited in the water thus creating a colloidal silver solution.

Buy Colloidal Silver: You can actually buy colloidal silver which has already been prepared and is ready for use. If you're purchasing colloidal silver, try to find a solution that has at least 30 PPM (parts per million) of silver. However, I can imaging that buying Colloidal Silver that is already prepared could get expensive.

Buy A Generator Kit: Another option is to buy a relatively cheap colloidal silver generator to make your own colloidal silver.This Colloidal Generator kit usually comes with everything you need including silver wire. All you need to do is provide the water and a container.

Make Your Own: You can make your own colloidal silver generator at home. The diagram below should illustrate what you need to do.

Items Needed:

* 9 volt battery (many people use 2 or even 3 batteries)
* 9v Battery Connector (less than $2 at a hardware or electronics store)
* Pure .9999 or 999 Silver (yes it must be pure)
* Distilled water (yes it must be distilled)
* Alligator clips (Optional: but will make things much easier)
* Soldering Iron (Optional: only needed if you want to use alligator clips)

The diagram above will show you how to easily make your own colloidal silver to make your own feminized cannabis seeds.

When you first connect everything, you may be surprised because it will seem like nothing is happening. You will know if it worked by the next day because the whole process will leave a silvery residue on your silver. You may need to use light sandpaper, brillo-pad, or something else rough to clean your silver each time after creating a batch of colloidal silver.

Remember to keep your resulting colloidal silver solution away from any light or it will deteriorate and turn a dark gray color. If this happens, then you can no longer use the solution for creating feminized seeds.

Avoid most problems when making colloidal silver by:

* using pure (distilled) water
* using pure (999/.9999) silver
* giving electrolysis enough time to work so you don't get a weak solution (at least overnight)
* making sure the solution has as little contact with light as possible until you use it


How to Feminize Seeds Using Rodelization:


* All-Natural
* Very Simple
* No cost


* Unreliable
* May not produce many feminized seeds
* Passes unreliable genetic tenancies to Hermie.

The Rodelization method is all-natural and is the simplest and most common method to create feminized seeds, but it is also unreliable and may not produce much pollen. Basically, the premise is that some female marijuana plants will start growing male pollen sacs / sex organs if they've been left in flowering too long (past the peak point of harvest). This is a last-ditch attempt by the marijuana plant to pollinate itself so that it at least produces a few seeds. You can collect these male pods and use the pollen inside them to pollinate other female plants. You pollinate female plants by evenly covering their buds with the pollen after they've been in flowering for 2-3 weeks. Females that are pollinated in this way will start growing all-female marijuana seeds. If you're very careful, you can pollinate only some of the buds on a plant which will produce seeds, and leave other buds alone so they can still be used for consumption.

This issue with this method is that some strains of plants never seem to grow male characteristics naturally. Additionally, with this method, you're selecting for plants that have a natural genetic tendency to show male characteristics, (tenancy to hermie). This can possibly produce seeds that are more likely to show male characteristics themselves which generally isn't what we want. Lastly, even when you do get male pollen sacs from a marijuana plant in this way, there tends to be a lot less pollen than from a typical male plant.

The one great thing about this method is it's completely all-natural so you can implement this strategy with an organic grow.
"I would.

I'd really like to meet an honest man.
But I'd have to lie to him cause I smoke pot."
______________________________ ______

First Outdoor Guerrilla Grow 2011
Understanding Ph.
Ingenious $4 Walmart Cloner.
SOG's DIY micro-cloning factory tutorial. (Very well illustrated and explained).
Handy site for the Gardener
(A wealth of information for any gardener).
Sometimes when I'm really medicated, I can really crack me up.
Stress_test is offline Quote

12 members found this post helpful.
Old 01-03-2011, 02:44 PM #2

blimblom's Avatar

Join Date: Mar 2010
Posts: 97
blimblom will become famous soon enough
nice reading . I dont think I ll ever do it , but I always love to know new things
blimblom is offline Quote

Old 01-03-2011, 05:28 PM #3

JWP's Avatar

Join Date: Mar 2006
Posts: 1,000
JWP is a jewel in the roughJWP is a jewel in the roughJWP is a jewel in the roughJWP is a jewel in the roughJWP is a jewel in the roughJWP is a jewel in the roughJWP is a jewel in the rough
Your just trying to be helpfull. Feminizing seeds is anythng but helpful to cannabis
JWP is offline Quote

0 members found this post helpful.
Old 01-04-2011, 03:24 PM #4

blimblom's Avatar

Join Date: Mar 2010
Posts: 97
blimblom will become famous soon enough
@JWP Feminizing can be very helpfull for quite many people. Why do you think its not??
blimblom is offline Quote

Old 01-05-2011, 01:47 AM #5
Briar Patch

Join Date: Feb 2009
Location: the basement
Posts: 34
Briar Patch is on a distinguished road
Thanks, very helpful.
Briar Patch is offline Quote

Old 01-05-2011, 01:53 AM #6
fuck the ticket, bought the ride

GreenintheThumb's Avatar

Join Date: Jan 2004
Location: CO you know
Posts: 1,493
GreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of lightGreenintheThumb is a glorious beacon of light
Originally Posted by JWP View Post
Your just trying to be helpfull. Feminizing seeds is anythng but helpful to cannabis
This isn't the forum for baseless comments like this.

I'm a Stanfield waiting, in a room with a Stringer while he stand on his word while I stand impatient, all this co-op talk all this sharing the pot, it sounds good til it's time for you to clear out your spot, nobody wanna retire nobody wanna proceed to, til I'm swinging clubs like go and pack up your people
GreenintheThumb is offline Quote

3 members found this post helpful.
Old 01-05-2011, 02:37 AM #7

Join Date: Feb 2006
Location: gilligans island
Posts: 13,142
supermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond reputesupermanlives has a reputation beyond repute
all females that show male parts should be culled. stress test females first then use whatever you want
supermanlives is offline Quote

Old 01-05-2011, 02:57 AM #8
collector of lightsabers.. and fine cannabis genetics

generalgrievous's Avatar

Join Date: Oct 2009
Posts: 805
generalgrievous is a jewel in the roughgeneralgrievous is a jewel in the roughgeneralgrievous is a jewel in the roughgeneralgrievous is a jewel in the roughgeneralgrievous is a jewel in the roughgeneralgrievous is a jewel in the roughgeneralgrievous is a jewel in the rough

... cut he/she last night... manually harvesting the nanners and using the fem pollen for s1's of my cut as well as another project or two ...

Used the CS method ...
"........just to recap ..........i come in peace ...i mean you no harm ...and you all will die .......Galaxar out!"
generalgrievous is offline Quote

4 members found this post helpful.
Old 01-05-2011, 03:34 AM #9
The Logical Gardener

Microbeman's Avatar

Join Date: Apr 2008
Posts: 4,442
Microbeman has disabled reputation
Thank you for taking the time to post this Stress-Test. To the other people unable to read - duh - please stick to the dummy forums.
Anybody can be wrong about anything.

"When the facts change, I change my mind.
What do you do, sir?"
"Capitalism is the astounding belief that the most wickedest of men will do the most wickedest of things for the greatest good of everyone."
~John Maynard Keynes~
Sorry: No questions by PM, check my webpage
Microbeman is offline Quote

2 members found this post helpful.
Old 01-06-2011, 08:06 AM #10

tokatronic's Avatar

Join Date: Nov 2010
Posts: 116
tokatronic is on a distinguished road
Here's the original thread:
tokatronic is offline Quote

Post Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT +2. The time now is 07:41 AM.

This site is for educational and entertainment purposes only.
You must be of legal age to view ICmag and participate here.
All postings are the responsibility of their authors.
Powered by: vBulletin Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.