Cannabis Sex Reversal Using Silver Thiosulphate (STS)

Photo compliments of @massmedicalstrains2.0

A lot of people have requested information about reversing the sex of a female plant to produce male pollen. The text from this post was pulled from the forums – Fet gets credit for much of the research and a kind (and currently unknown member) assembled it as it appears below.

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. Check out Robert Clarke’s “Marijuana Botany”, which is a very good reference.

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. Also, order from Heaven’s Stairway. Not that they need a plug from me, but they are very professional and provide very fast service worldwide.

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.

Application:
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.

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 trials it took 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 for the plant for it to stay healthy.

Effects:
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 seemed 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 accidently. Point downwind; don’t let it get on your hands or clothes.

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 carefulollen is sneaky. After 4-5 days, the bag is gently removed and the plant completes it’s flowering cycle.

Yet another method 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.

Here are links to some safety data. A Google search will bring up more information if needed.

Silver Nitrate info:
ICSC:NENG1116 International Chemical Safety Cards (WHO/IPCS/ILO) | CDC/NIOSH
http://www.lions.odu.edu/~redwards/… solution.pdf

For a realistic hazard level comparison, here is a link for the safety and handling data for Ammonium Nitrate, or common fertilizer:

Sodium thiosulfate is also a white crystalline chemical commonly used in photography; it is used in photographic fixers. Same general cautions apply, minus the staining. This formula uses the anhydrous type. Non-hazardous.

Sodium Thiosulfate info: http://ptcl.chem.ox.ac.uk/MSDS/SO/s…hiosulfate.html
http://www.med-chem.com/MSDS/Sodium_Thiosulf.htm

——————
Where to get the chemicals:

Photographic chemicals, photo chemistry, photo processing equipment, photo chemicals

silver nitrate: 10 grams: $10
http://www.photoformulary.com/Deskt…yID=27&langID=0

sodium thiosulfate (anhydrous): 100 grams: $3.95
http://www.photoformulary.com/Deskt…yID=28&langID=0


Have fun experimenting with this technique. Use it responsibly. There are a few good threads here at CW that go into the pros and cons of transsexual agents and feminized seeds. Read them. And most importantly, use STS with quality F1 strains developed by professional breeders for the most consistent results.

A huge thanks to Fet from Spice Brothers Seeds for his help and advice in using this technique. I simply brought together available information from previous posts and tried my own recipe. I’m thrilled to share the results. Future tests will be done to adjust the formula so the molar ratios of the chemicals are correct, as specified by Gobgoober (thanks, Gob) but the formula posted here is completely effective.

Matt Riot’s Advanced Seed Germination Tutorial

My special guest this issue is Matt Riot, who has kindly offered to share his Advanced Seed Germination Tutorials with you good folks. Not everyone is going to want to follow these instructions, but for rare, expensive, or older beans this information is top level stuff.

Matt is the owner of Riot Seeds “The 1st and Only Punk Fucking Rock Seed Company”. Matt has been in the game for a long time and works with some fine genetics – you can find him on Instagram @riotseedco – there are 3 short videos and I’ve posted them in order.

ADVANCED SEED GERMINATION

By Matt Riot @riotseedco

Breeding Males – Advanced Selection Tip

There is a trick…more like a technique, that can help in any breeding project.

This information was passed to me (and others) by someone well known to the breeding community, and we were asked not to share it. However if any of you have read the ‘My Best’ thread, you know I am on my way out the door and am passing my best old school genetics around so the ‘new generation’ of breeders and smokers can beneift…as well as my old stoner friends lol.

I have also decided to divulge this information after much consternation and angst, because I am not sure if it will ever become public domain if I do not, and I fully believe it should be. This is/was a very difficult decision to make. But hey, WTF, it is what it is. People who are interested should know. Hoarding information is as bad as hoarding clones.

The first person I know of to use this breeding technique in the MJ world was a man named Nevil Schoenbottom, who passed it to Shantibaba, who passed it to another person who passed it to me(and others). The trick is using what some breeders ‘in the know’ call recessive males.

No one I know of who got this information paid much attention to it, or at least ran with it. The only reason I am different is because I stumbled upon a recessive male by accident but didn’t realize what I had found until after a few crops of outcrossing him and noticing I was getting all the traits I wanted passed to the offspring. I suddenly realized what I had in a rare moment of clarity. As a bonus the dominant traits he passed were increased potency and tighter buds. I think this was just a fluke though.

I am no expert in genetics at all, in fact my knowledge is rudimentary, but this is how it was explained to me.

Recessive males are males that have a large number of double recessive genes for the traits most sought after by MJ breeders. Ie aa as opposed to Aa or AA. If you know something about genetics there should be a light bulb going on right now.

When males that have recessive genes for the traits we want passed from the mother, because they are dominant in the mother they will combine as Aa. ‘A’ from the AA mother and ‘a’ from the father, and express the trait you want to see in all of the F1 female offspring. There will also be males from the offsrping that combine the same way for this trait ie Aa. If these two sibling plants are combined, using P-Squares we can see there will be a certain % which combine as AA and the trait will be fixed by breeding these offspring. This really eliminates a lot of work.

Fine in theory Roz(I hear you saying) but how can I find and identify these males? This is key to the application. This information was never passed to me or the others that were privy to the recessive male concept and is perhaps why no one did anything with it. But I will pass it to you now.

These males can be identified easily in some cases, because unlike dominant males which flower earlier than sibling females the recessive males flower later. In addition, it stands to reason that if Shantibaba uses this technique, these males can be found in larger numbers within his seedstock. So there it is, with apologies to Shanti, Nevil and the person who told me about it.

If you have an in depth understanding of genetics and don’t believe this or consider it anecdotal only, feel free to express those ideas, but I will not argue it with you. I am only passing on what was told to me and found that at least in my case it was true.

Best wishes and best of luck to you all.

Cheers,
R