Just Thought I'd Throw Up Some Pics of Where I'm at Right Now

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. Here is a link to Robert Clarke's "Marijuana Botany", which is a very good reference.

"Marijuana Botany" by Robert Connell Clarke
(unfortunately missing the appendices)

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.



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