How to Make Feminized Cannabis Seeds: A Guide to STS and Feminized Seed Production

Feminized cannabis seeds have transformed modern cannabis cultivation, allowing growers to produce female plants without the time, space, and expense of identifying and removing males. But how are feminized seeds actually made, and what separates high-quality feminized genetics from poorly bred seeds?

At GTR Seeds, we specialize in breeding feminized cannabis seeds, including F1 hybrids and triploid varieties rich in THC, CBD, CBG, THCV, CBDV, and CBGV.

One of the most important tools in our breeding program is silver thiosulfate (STS), which allows breeders to produce pollen from genetically female plants.

Here's how the process works, why genetic selection matters, and what growers should understand before attempting to make their own feminized seeds.

What Are Feminized Cannabis Seeds?

Feminized cannabis seeds are produced through breeding techniques designed to generate predominantly female offspring.

Under typical conditions, cannabis plants develop as either male or female. Female plants produce the cannabinoid-rich flowers most growers want, while male plants produce pollen used for reproduction.

By using pollen produced from a genetically female plant, breeders can create seeds with a very high probability of developing into female plants.

Properly bred feminized seeds make cultivation more efficient, reducing the need to identify and remove male plants and allowing growers to devote more space to flower production.

Step 1: Selecting Female Parent Plants

Making quality feminized seeds begins long before pollen production.

At GTR Seeds, we take parent selection extremely seriously. Our breeding program relies on carefully selected parental lines that have undergone multiple generations of breeding, evaluation, and selection.

We look for desirable characteristics, including:

• High cannabinoid production

• Desirable terpene profiles and aromas

• Vigorous growth and strong plant structure

• Consistent flowering and maturation

• Genetic stability and resistance to unwanted intersex expression

Our goal is to develop genetically consistent parental lines that produce reliable, true-to-type F1 hybrid offspring.

The quality of feminized seeds depends heavily on the genetics used to produce them. Simply reversing a female plant does not guarantee that its offspring will perform consistently.

Step 2: Producing Pollen From Female Cannabis Plants

The next step involves inducing a genetically female plant to produce pollen-bearing flowers, a process known as sex reversal.

Several techniques can accomplish this, but not all produce equally reliable results.

Silver Thiosulfate (STS)

Silver thiosulfate, commonly called STS, is the method we use at GTR Seeds.

STS is a silver-based chemical treatment that interferes with ethylene signaling, a hormonal pathway involved in female flower development.

When appropriately applied to a genetically female cannabis plant, STS can induce the development of pollen-producing flowers.

Because the treated plant is genetically female, its pollen generally carries X chromosomes rather than the X- or Y-bearing pollen produced by typical male plants.

This makes it possible to produce predominantly female offspring when that pollen fertilizes another genetically female plant.

Colloidal Silver

Colloidal silver is another method used by cannabis breeders to induce pollen production on female plants.

Like STS, it interferes with ethylene signaling. However, treatment consistency and effectiveness can vary depending on the formulation and application.

Stress-Induced Pollen Production

Historically, some growers attempted to produce feminized seeds by exposing female plants to environmental stress, such as interrupted light cycles or other unfavorable growing conditions.

While stress can trigger pollen production in certain plants, this approach is generally less predictable and may select for undesirable intersex tendencies.

Early feminized seeds developed a reputation for instability partly because of poor parental selection and unreliable breeding practices.

Modern feminized seed production has improved significantly through controlled sex reversal and rigorous genetic selection.

Important: Silver-based treatments should be handled with appropriate protective equipment and precautions. Treated plants should not be consumed or used for flower or extract production.

Step 3: Pollinating Female Cannabis Plants

Once a reversed female plant develops mature pollen-producing flowers, its pollen can be collected and used to fertilize another female plant.

Because both parents are genetically female, the resulting seeds are expected to produce predominantly female plants.

Breeders can use this technique to produce different types of feminized seeds, including self-pollinated lines and feminized F1 hybrids.

At GTR Seeds, much of our breeding focuses on feminized F1 hybrid cannabis seeds.

By crossing carefully selected parental lines, we aim to combine desirable characteristics such as vigor, cannabinoid production, flower quality, and uniformity.

This is an important distinction: feminization determines the expected sex of the offspring, while the breeding strategy and parental genetics determine many of the characteristics growers actually care about.

Step 4: Harvesting and Testing Feminized Seeds

After successful pollination, seeds develop and mature within the female flowers.

Once mature, they are harvested, cleaned, dried, and prepared for storage and germination testing.

At GTR Seeds, germination testing is an important part of our quality-control process. We also use independent third-party germination testing to evaluate our seed lots.

Interestingly, not all cannabis seeds reach their maximum germination potential immediately after harvest.

We've observed that some of our triploid varieties benefit from additional post-harvest maturation and storage time, with germination rates continuing to improve for several months after harvest.

This is one reason seed testing and post-harvest handling matter just as much as the initial breeding process.

Growers interested in improving germination can also read our guide to starting cannabis seeds.

Step 5: Selecting for Genetic Stability

One of the most common questions about feminized cannabis seeds is whether they are more likely to develop hermaphroditic or intersex flowers.

Properly produced feminized seeds are not inherently unstable.

The risk of unwanted pollen production depends heavily on the genetics involved, environmental conditions, and the breeding program used to develop the seeds.

At GTR Seeds, we actively evaluate our breeding lines for genetic stability and remove lines that demonstrate undesirable intersex tendencies.

Our goal is to produce feminized genetics that growers can trust, whether they are planting a small home garden or a commercial field.

Advantages of Feminized Cannabis Seeds

Feminized seeds offer several important benefits over regular cannabis seeds.

• More productive growing space: Nearly every plant is expected to produce female flowers rather than requiring the removal of males.

• Less time spent sexing plants: Growers can avoid much of the labor associated with identifying and removing male plants.

• Predictable crop planning: Feminized genetics help growers plan planting density, plant counts, and harvests.

• Excellent for F1 hybrid breeding: Feminization can be combined with carefully developed parental lines to produce consistent, vigorous hybrid offspring.

For growers focused on flower production, these advantages can translate into more efficient cultivation and better use of available resources.

Are There Any Disadvantages to Feminized Seeds?

Although feminized seeds are an excellent choice for most flower growers, there are some considerations.

Genetic stability: Poorly selected parental plants may produce offspring with undesirable intersex tendencies. This is why careful breeding and testing are essential.

Breeding flexibility: Growers interested in producing conventional male and female breeding populations may prefer regular seeds.

Genetic diversity: Feminization itself does not necessarily reduce genetic diversity, but individual breeding methods, such as repeated self-pollination, can increase homozygosity.

Ultimately, the quality of a feminized seed depends on the breeding work behind it.

Frequently Asked Questions About Feminized Cannabis Seeds

Can you make feminized seeds without STS?

Yes. Colloidal silver and certain other approaches can induce pollen production in female plants. However, STS is widely used by professional breeders because it can provide controlled, repeatable sex reversal.

Are feminized cannabis seeds 100% female?

Feminized seeds are expected to produce overwhelmingly female plants, but no breeding process guarantees that every seed will develop into a perfectly stable female plant under every condition.

Can you make feminized seeds from any female cannabis plant?

Many genetically female cannabis plants can be induced to produce pollen, but the results vary. Pollen production, fertility, and offspring quality depend on the genetics and treatment response of the parent plant.

Do feminized seeds produce higher yields?

Feminization does not automatically increase the yield of an individual plant. However, it can improve overall crop efficiency by reducing the number of unwanted male plants.

Are feminized seeds genetically identical?

No. Feminized seeds are not necessarily clones or genetically identical. Feminized F1 hybrids can combine genetic material from two distinct female parental lines and produce offspring with traits inherited from both.

Can triploid cannabis seeds be feminized?

Yes. Triploid cannabis seeds can be produced using feminized breeding approaches involving appropriately selected parental plants with different chromosome counts.

Triploid breeding is more complex than conventional diploid breeding, but it offers opportunities to develop distinctive varieties with reduced fertility and desirable production characteristics.

Growers can explore our triploid cannabis seed collection to learn more.

Watch: How We Make STS for Feminized Seed Production

Want to see more of the process?

In the video below, we demonstrate how we prepare silver thiosulfate for use in our cannabis breeding program.

Video: How to Make STS for Feminized Cannabis Seeds

Understanding how feminized seeds are made provides a useful look at the science behind modern cannabis breeding.

Why Quality Feminized Genetics Matter

Making a feminized cannabis seed is one thing. Producing thousands of consistent, vigorous plants with desirable cannabinoid profiles, aromas, and growth characteristics is another.

At GTR Seeds, our breeding program combines carefully selected parental lines, controlled feminization, F1 hybrid development, and germination testing.

Whether you're interested in making your own feminized seeds or growing professionally bred genetics, understanding the process helps you make better decisions about the seeds you plant.

Explore our cannabis seed collections to learn more about the different cannabinoids, genetics, and breeding approaches available to growers.