Feminized Seed Production with Raw Genetics

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A Quick How-To on Silver Thiosulfate (STS)

Hello, fellow enthusiasts! I’m excited to share some behind-the-scenes insights from Raw Genetics. Today, I’ll delve into one of our core techniques—using Silver Thiosulfate (STS) to reverse the sex of our plants, enabling us to produce feminized seeds.

Why We Use STS at Raw Genetics

At Raw Genetics, we prioritize the practical benefits of feminized seeds, which streamline our breeding and selection processes. Creating your own STS mix is easy and cost-effective. This method eliminates the need to remove male plants, conserving space and resources and enhancing the efficiency and speed of the selection process.

Ordering STS

I typically order these two components: as long as the sodium thiosulfate is anhydrous, you can source it from any reliable supplier. From my experience, silver nitrate crystals are consistent across different suppliers, and there are many options available for ordering both parts of the mix.

Silver Nitrate Crystals – The Science Company

Sodium Thiosulfate Anhydrous – The Science Company

My Recipe for Preparing STS

Preparing the STS solution is straightforward, but it’s important to follow the protocol to ensure optimal results. Here’s how:

Reversal Solution – Silver Thiosulfate (Anhydrous)

  1. Start with a Pyrex jar and fill it with 500 mL of distilled water (preferred) or RO water (ensure filters are clean and water is 0 ppm).
  2. Add 0.5 grams of silver nitrate, stirring until completely dissolved—this typically takes about 30 seconds.
  3. Transfer this solution to a light-sensitive brown jar and label it “A”. Remember, Solution A is light-sensitive and loses potency over time.
  4. Fill another jar with 500 mL of distilled or RO water.
  5. Add 2.5 grams of sodium thiosulfate (Anhydrous), stirring until fully dissolved.
  6. Label this second solution “B”.
  7. After thoroughly cleaning all measuring instruments and containers, prepare the working solution:
    • Pour 50 mL of Solution B into a clean cup.
    • Add 50 mL of Solution A while stirring.
    • Label the resulting mixture “C”.
  1. To finalize, add 500 mL of distilled or RO water to “C” to create “D”, a diluted stock with a 5/1 ratio of “C” to water.
  2. It is recommended to store Solutions A and B in the refrigerator and in the dark. Adjust the mixing ratios based on your reversal requirements.

Application Techniques at Raw Genetics

We apply the STS solution (“D”) during the vegetative stage, starting about 2 weeks before switching the light cycle to initiate flowering. Continue spraying the reversed plants for an additional two weeks before starting flower on the pollen-receiving plants. We spray our plants daily or every other day until day 21 of flowering, when pollen typically begins to show. The frequency of applications and ratios of the mix may be adjusted based on each plant’s response.

It’s advisable to have a separate space for staging the reversal to manage the corresponding plants that will receive pollen. We typically flip the females on days 14-16 of flowering the reversal plants. This helps ensure the reversed plants align with the cycle of the pollen-receiving plants. Pollen production on most reversed plants takes about 5-6 weeks.

Simple Guide to Reversing Plant Sex with STS

  1. Pre-Flower Preparation: Start spraying STS on the plants you want to reverse for two weeks during their vegetative stage before they enter the flowering stage.
  2. Initiate Flowering: Begin the flowering phase for these plants and continue applying STS regularly. Allow these plants to flower for two weeks before starting the flowering process for the plants that will receive the pollen. This scheduling ensures the plants are synchronized for optimal pollination.Note: It’s advisable to prepare and stage any plants intended to receive pollen at the start of this process if you’re planning a live pollination.
  3. Regular Application: In my experience, more frequent spraying can be crucial, especially with new plants, to ensure effective sex reversal. Adjust the frequency of application as needed—from daily to once every third day. For first reversals, more frequent spraying is recommended.
  4. Observing Pollen Production: Typically, it takes about 5 to 6 weeks to see pollen production. This is why advanced staging is crucial for live pollination. Note that timing can vary depending on plant genetics.
  5. Patience is Key: Achieving successful results requires patience and consistent care. Stay committed and observant throughout the process. For more detailed guidance and support, consider joining our community.

Safety and Professionalism

Handling STS requires careful attention at Raw Genetics. We always use gloves and eye protection during preparation—PPE is key to ensuring your safety. Remember, plants treated with STS are solely for seed production and are not intended for consumption.

Wrapping Up

Using STS is just one of the many techniques available for reversing plants in today’s market. There are a variety of premixed sprays and other methods to deliver silver for reversals. A quick Google search can provide more information.

I hope this provides a glimpse into the techniques we use at Raw Genetics to ensure the highest quality in feminized seeds. Stay tuned for more insights and happy growing!


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