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The Link Between Colloidal Silver And Feminized Cannabis Seed

The most powerful benefit of cannabis legalization is the potential for research. This paper covers the biology of cannabis in the presence of colloidal silver, a compound that alows cannabis to change from male to female. This allows cannabis growers to only produce flowering female plants with more than 90% certainty.


Samuel Bonne

4 months ago | 14 min read


What is Colloidal Silver?

Colloidal silver is a solution containing pure silver nanoparticles (AgNPs) in an aqueous medium. The solution is commercially sold, with the silver nanoparticles suspended in demineralized water or other liquids. In the cannabis community, colloidal silver is used as an agent to make feminized seeds.  However, several studies[1] [2] also showed that an excess of colloidal silver could lead to phytotoxicity (toxic effect from exposure to a substance). 

Uptake of Colloidal Silver

According to the International Journal of Molecular Sciences, [1] when spraying a fine mist of colloidal silver onto the plant, AgNPs penetrate the cell wall and plasma membrane of the epidermal layers in the leaves. Following a series of actions, AgNPs enter the xylem (vascular system) and move to the stele and translocate to the leaves and nodes of cannabis plants. AgNPs can leach silver ions, Ag+ or Ag(I) ions into the surroundings through the oxidation of zero-valent silver. During the uptake and translocation of AgNPs, Ag(I) is released, leading to oxidative stress and disturbing cell function. It should be noted that when applying AgNPs to the leaves and branches of cannabis plants, only small-sized AgNPs can pass through the pores of the leaves. Moreover, the cell wall of cannabis plants is a porous network made of polysaccharide fiber matrices, acting as a natural permeable barrier. Again, only small-sized AgNPs can enter plant cells, and release some Ag(I). However, excess silver deposit on the leaves and branches of cannabis plants can block the stomata, preventing transpiration to occur.

In some instances, growers apply colloidal silver to the roots of cannabis plants. AgNPs take longer to reach the developing nodes of the cannabis branches since AgNPs must be transported via intercellular spaces of the roots, before penetrating the xylem. The longer approach may lead to intersexual flowers (exhibiting both male and female expressions) instead of male-induced pollen sacs. Additionally, AgNPs can be transported via the plasmodesmata process. However, an excess of silver particles aggregates in the cell wall and plasmodesmata, blocking intercellular communication. The prolonged blockage of AgNPs may affect nutrient intercellular transport among tissues.

Phytotoxicity of colloidal silver

Obtaining the perfect balance for colloidal silver can be a challenging task. A low concentration of colloidal silver does not trigger male-induced flowers throughout the whole plant while high levels of colloidal silver may cause phytotoxicity in cannabis plants, leading to wilting and dying. An Yan et al.[1] stated that after exposing plants to AgNPs, they observed significant changes in plant morphology. By assessing the growth potential, biomass, germination of seeds and surface area of the leaves, the results showed that AgNP exposure can inhibit root growth and seed germination. Decreasing biomass and root abscission of rice, zucchini and wheat were also noted when exposed to a high concentration of >100 mg/L of AgNPs. 

On a physiological level, An Yan et al. discovered that AgNPs could reduce chlorophyll levels and nutrient uptake in leaves. The disruption of chlorophyll synthesis affected the photosynthetic system of the plants which resulted in an inhibited plant growth. A decline in transpiration rate and hormone alteration were also discovered. The results coincide with previous studies from Tripathi et al., where blockage of stomata prevented transpiration among autotrophic plants (use photosynthesis for nutrition). The alteration of endogenous hormonal interaction includes Ag(I) inhibiting ethylene for sex expression among cannabis plants (more on that below). One of the main drawbacks of excess AgNPs is the significant decrease in chlorophyll content which disrupts the balance of essential elements in leaf gametophytes. 

Evidence also points towards the genotoxicity and cytotoxicity impact of AgNP exposure on plants. Yin et al.[1] found that plant growth inhibition was also accompanied by cell structure alteration and cell division. Pokhrel and Dubey[1] found that the presence of AgNPs in plant cells decreased the size of the vacuoles. With smaller vacuoles, the size and turgidity of plant cells in maize and cabbage were reduced. The findings matched the results of Mazumdar where both cell walls and vacuoles were damaged. AgNPs can also impact the mitotic index and impair cell division which led to chromatin bridges, disruption of metaphase and numerous chromosomal breaks. 

It is also crucial to maintain optimum levels of colloidal silver to prevent damage during pollen formation. Speranza et al.[2] discovered that AgNPs dissolved in Ag(I) ions which increased hydrogen peroxide levels (H2O2) among pollen culture. The increase in Ag(I) also caused damage to pollen membranes which inhibited germination. Speranza discovered that the impact of Ag(I) on germination was far greater than AgNPs, suggesting that Ag(I) can also impact physicochemical and chemical interactions. The disrupted interactions with nucleic acid may induce changes and damage to cell DNA. Besides, gene expression profiles of AgNPs and Ag(I) were analyzed by microarray. The results stated that there was a significant overlap between altered gene expression in the two treatments which explained the similarities in plant responses. According to Mura et al.[2] colloidal silver is oxidised in water and forms bonds with anions, transforming into complex anions or heavy metals. The presence of both anion complexes and heavy metals can cause multiple toxic effects on living organisms, including humans. Therefore, plants treated with colloidal silver cannot be used commercially due to their high silver concentrations. 

How Does Colloidal Silver Help in Making Feminized Seeds?

Colloidal silver interacts with a hormone called ethylene to trigger a change in the sex of cannabis plants. Sex expression in cannabis plants is regulated by genes, hormonal and environmental factors. According to Heslop-Harrison in 1964[3], their research showed that specific endogenous hormones such as gibberellins, ethylene and auxin play a crucial role in sexually polymorphic systems. While cannabis plants are dioecious, meaning that male and female blossoms are on separate plants, stressors that affect hormones in the plants can cause a change in their sex expression.

Usually, ethylene, auxin, and cytokinins favour female expressions in plants (two bracts at the nodes of cannabis plants) and gibberellins promote male sex expressions (pollen sacs at the nodes) (Mohan Ram 1964)[3]. In another research, Byers in 1972[4] found that treatments reducing ethylene concentrations in plants or antagonise ethylene interactions can lead to the formation of bisexual or male flowers instead of female plants. He used CO2 as the antagonist of ethylene instead of silver ions. However, in 1976, Beyers[5] (another researcher. The names are confusing lol) found that silver ion (Ag(I)) has a greater interference on ethylene actions than CO2. Ag(I) ions bind at the receptor sites of ethylene which prevents ethylene from starting a series of enzymatic reactions. 

Beyer tested the effects of silver using silver nitrate (AgNO3) on gynoecious cucumber and tomato plants. He found that silver ions have a greater effect on male flower induction in cucumber than gibberellin (GA3). With the newfound interest of silver ions on male sex expression, Veen and Van de Geijn, in 1978, analysed the performance of AgNO3 and silver thiosulphate (STS) anions on ethylene among carnations (a type of flower). They found several benefits of STS compared to AgNO3.

  1. STS was transported much faster than AgNO3  
  2. STS completely counteracted the effects of ethylene on the plants
  3. STS extended the vase-life period of carnations. 

Since evidence pointed towards silver nitrate and silver thiosulphate effects on male sex expressions, Sarath and Mohan Ram[4] analysed the performance of silver ions in female cannabis plants. Their study aimed to assess the performance of STS and AgNO3  on cannabis plants and their optimal dosage for Cannabis plants. Mohan Ram used aqueous solutions of AgNO3 and STS on growing shooting tips of female cannabis plants with a 0.01 ml pipette. 

The optimal dose of AgNO3  and STS on female cannabis plants

To find out the optimal dose of AgNO3 and STS, Mohan Ram[4] used a concentration of 25, 50, and 100 μg (micrograms) of STS and 50, 100, and 150 μg of AgNO3  on ten plants for 5 days. The control plants were given a surfactant solution only. 

Figure 1a [3]

STS results

After five days, they found that both 25 and 50 μg of STS was not enough to change sex expression throughout the whole plant. The only observation found was the black colour of the shoot tips and the shape of the leaves changed and a few male flowers. However, at 100 μg, Mohan Ram noted promising changes:

  1. The first three lower nodes of the plant showed male sex expressions, meaning that the presence of pollen sacs was observed.
  2. The plants bore a large number of altered male flowers and some female flowers.
  3. In each branch, the altered flowers were found in the upper nodes, leading to a cluster of male flowers towards the top of the cannabis plants.

Figure 2a [3]

Figure 2b 

AgNO3  Results

For both 50, and 100 μg of AgNO3, Mohan Ram observed that the number of nodes on the plants was much higher than the control. Especially in the 50 μg plant, the branches bore flowers of the following sex types:

  • Female flowers
  • Intersexual flowers (both male and female expressions, stamens and anthers)
  • Reduced males flowers (4 or fewer stamens: an organ that produces pollen)

The main difference between 50 and 100 μg of AgNO3, was the number of male flowers found at the nodes of the branches. As expected, 100 μg showed a higher number of male flowers with fewer reduced males and female flowers. Mohan Ram reported that there was a distinct change in the sex expressions of flowers on the main axis (stem) of mature plants after the 5-day treatment.  

Yet, at 150 μg, the shoot tip of the cannabis plants was black and dried up after five days. Mohan Ram also noted that the shooting tip could not be revived. The lower nodes of the plants were highly stimulated by the high concentration of silver, resulting in bushy plants. 

We can conclude that for both STS and AgNO3, a concentration of 100 μg was optimal in female cannabis plants. For colloidal silver products on the market, you can choose 100 ppm colloidal silver since the concentration of silver is 100 μg. For optimal dosing, 100 ppm is a good rule of thumb. However, if you want to experiment on your strain, you can choose a range of concentration around 100 ppm, e.g 80, 90, 100, 110, and 120 ppm. Since there is a small possibility that silver ions are transported at a different rate according to the strains, you can experiment to find the ideal colloidal silver for your cannabis plants. In contrast, if you do not want to experiment, 100 ppm colloidal silver works perfectly for all female cannabis plants. 

The performance of the altered pollen grains

Figure 3. Germinating pollen grains from male-induced flowers by AgNO3  from 100 μg treatment

Mohan Ram[4] also found that irrespective of the extent of male sex expression of the plant, (male, reduced male, or intersexual) the anthers of the altered flowers produced a significant quantity of viable pollen grains. To test if the pollen grains were still viable to produce cannabis plants, Mohan Ram incubated the pollen grains in an agar-sucrose medium. The pollen grains germinated within 30 minutes of incubation. 

They also tested the ability of the altered pollen for pollination and germination to produce effective seeds. Mohan Ram hand-pollinated the stigmas of female flowers with the pollen from altered male flowers. The female flowers developed seeded fruits from which the progeny of the seeds were 100% pistillate (feminized). 

Since the genetics of both parents (male-induced flowers and female flowers) both contain X chromosomes (female chromosome), all of the seeds obtained are feminized. For modern-day application, colloidal silver is finely sprayed on a female cannabis plant to decrease the levels and effects of ethylene. Usually, colloidal silver is added to the beginning stages of the flowering phase. With lower levels of ethylene, the plant is induced to male sex expressions on the nodes of the plant. To identify if the colloidal silver is working, pollen sacs will be formed at the nodes of the apex (stem) of the plant). When pollinating other female plants with the pollen sacs formed at the nodes, the seeds produced are ensured to be females. 

The relationship between silver ions and ethylene 

The research from Mohan Ram[3][6] showed that STS was more effective than AgNO3 to induce male sex expressions on female cannabis plants. Additionally, the number of male flowers produced and the percentage of male flowers and reduced male flowers per plant were much higher in the STS treatment. Another study from Veen in 1979[7], showed that STS inhibited the effect of ethylene on senescence and abscission in carnations which significantly extended their vase-life. Furthermore, Mohan Ram[3] also showed that silver in an anionic complex could be more efficient than silver in cationic form. Since STS triggered male sex expression in female plants, Mohan Ram stated that chemical induction is a promising means to produce female plants. AgNO3 and STS approach could also maintain the gynoecious lines of female cannabis plants by developing feminized seeds.

Silver ions applied to dioecious plants as AgNO3 or STS inhibits the function of ethylene. Famous research from Beyer in 1976 found that an excess of ethylene was demonstrated in a triple response. The response included growth retardation, swelling of the stem and horizontal growth. However, the presence of AgNO3 decreased growth retardation and abscission among the treated plants. Beyer stated that ethylene is a crucial hormone involved in various developmental processes such as growth, flowering, abscission (shedding of leaves and seeds), and sex expression. According to Beyer’s study, the presence of Ag(I) ions from AgNO3 solution inhibited the actions of ethylene effectively. Additionally, the properties of Ag(I) surpassed the effects of CO2 on ethylene, a famous ethylene antagonist. 

From the study, Beyer[5] found that as the concentration of AgNO3 increased, the characteristics of ethylene, the triple response, were gradually and consistently reducing. The degree of protection of AgNO3 on plants treated with ethylene was astonishing since the plants underwent several ethylene responses before AgNO3. Beyer also observed that the Ag(I) effect on the growth of plants was systemic along with the stimulated abscission of leaves by ethylene. Plants without the AgNO3 treatment had shed all of their leaves on the 7th day due to ethylene. However, plants that were treated with ethylene and increasing levels of AgNO3 gradually showed less leaf abscission. Moreover, excess ethylene had a growth-retardation effect on the plants and AgNO3 slightly reduced ethylene effects. Beyer also analyzed the effects of ethylene on flower senescence (ageing of flowers). Orchid flowers were treated with AgNO3 for 2-3 days before being exposed to a high concentration of 0.2 μl/litres of ethylene for 24 hours. In contrast, control flowers were only treated with 24-hr ethylene exposure. The control flowers died after five days due to flower senescence[7][12] induced by ethylene while AgNO3 flowers remained in excellent condition. Beyer found that the high concentration of AgNO3 led to sepal damage while the low levels of AgNO3 did not offer enough protection against ethylene. 

Figure 4[9]. Interaction between ethylene and copper

The outstanding properties of Ag(I) on ethylene are its specificity, persistence and lack of phytotoxicity during optimum concentrations. Besides, in another study, Beyer also discovered that Ag(I) completely blocked the actions of ethylene in cucumber and tomato plants[8]. The research stated while the protection of Ag(I) was still unknown, Ag(I) did not have a scavenging effect on ethylene as the ethylene levels remained constant when both entering and leaving the chamber. Additionally, Ag(I) binding to ethylene is not irreversible compared to mercury (Hg(II), which has marginal irreversible effects on blocking ethylene. Contrarily to CO2, which shows a competitive inhibition of kinetic conduct, the moderate ethylene antagonist, Ag(I), has a non-competitive behaviour. Evidence[5][8][9] shows during the metabolism of ethylene through oxidation, the mechanism involves a metal-ion system. The receptor site of ethylene in plants has metallic properties. Additionally, copper, Cu(I) is proposed to bind with the metal receptor site because ethylene is known to form complexes with Cu(I). Therefore, Beyer[5] suggests that Ag(I) substitutes Cu(I) in the metal receptor site, interfering with the oxidation of ethylene, thus affecting ethylene action in the plant. Since both the oxidation state, the similar size and ability to form Ag(I) complexes with ethylene, Beyer theorizes that Ag(I) is the ideal substitute for Cu(I). 

Ethylene And Sex Expression In Cannabis Plants

Galoch[10] did a study in 1978 to analyze the hormonal control of sex expressions in dioecious hemp plants (Cannabis Sativa). Galoch stated that ethrel (a compound releasing ethylene) and auxin had an important influence on sex expression in both male and female hemp plants. According to Heslop-Harrison[3][10], both auxin and ethylene promote female tendency among various plant species, for both mono and dioecious plants. Galoch based the study on Heslop-Harrison research to analyse sex expression among female cannabis plants. From the study, cannabis plants treated with auxins showed an increase in feminization. When combined with IAA (indole-3-acetic acid), auxin triggered the development of female flowers and intersexual flowers, having both female and male flower components, on male hemp plants. Similarly to auxins, ethrel, induced feminization on male plants. The findings of the study were in agreement with the results from the Mohan Ram study on cucurbits. Galoch stated that auxins enhance the production of ethylene in plant tissue. 

Furthermore, the effects of ethylene were analyzed on male-induced watermelon flowers to assess the change in sex expression towards female plants[11]. The addition of ethylene partially or fully restored the original gynoecious sex expression to produce only pistillate flowers. The results suggest that ethylene plays a key role in determining sex expression. Byer[4] also stated that femaleness is regulated by endogenous ethylene since the flowers exposed to CO2, a competitive ethylene inhibitor, showed an increase in maleness. The action of ethylene follows a logarithmic function to its concentration. Therefore, a 5-fold reduction of ethylene levels from a saturating level may provide sufficient ethylene for the plant to be biologically active. At the optimal level, the mechanism of ethylene will not be affected by the weak antagonist CO2, even at a high concentration. Similar to Galoch, Byer’s study also concluded that the endogenous concentration of auxins may determine the endogenous levels of ethylene in the plant. The direct correlation makes ethylene an intermediate effector molecule that promotes femaleness among most dioecious plants. However, Byer also noted that modifying sex expression failed when the atmospheric pressure was decreased, reducing the concentration of gibberellin, ethylene, and auxin. Chemical sex expression provides an auspicious method to maintain genetically pure gynoecious lines (having only female flowers and female pollen). 


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(2) Kong, I. C.; Ko, K.-S.; Koh, D.-C. Evaluation of the Effects of Particle Sizes of Silver Nanoparticles on Various Biological Systems. Int. J. Mol. Sci. 2020, 21 (22), 8465.

(3) Mohan Ram, H. Y.; Sett, R. Induction of Fertile Male Flowers in Genetically Female Cannabis Sativa Plants by Silver Nitrate and Silver Thiosulphate Anionic Complex. Züchter Genet. Breed. Res. 1982, 62 (4), 369–375.

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(5) Beyer, E. M. A Potent Inhibitor of Ethylene Action in Plants. Plant Physiol. 1976, 58 (3), 268–271. 

(6) Mohan Ram, H. Y.; Sett, R. Modification of Growth and Sex Expression in Cannabis Sativa by Aminoethoxyvinylglycine and Ethephon. Z. Pflanzenphysiol. 1982, 105 (2), 165–172.

(7) Veen,H ; van de Geijn, S. C. Mobility and Ionic Form of Silver as Related to Longevity of Cut Carnations. Planta 1978, 140 (1), 93-96

(8) Iwahori, S.; Lyons, J. M.; Smith, O. E. Sex Expression in Cucumber Plants as Affected by 2-Chloroethylphosphonic Acid, Ethylene, and Growth Regulators. Plant Physiol. 1970, 46 (3), 412–415.

(9) Smith, A. R.; Hall, M. A. Mechanisms of Ethylene Action. Plant Growth Regul. 1984, 2 (3), 151–165.

(10) Galoch, E. The Hormonal Control of Sex Differentiation in Dioecious Plants of Hemp (Cannabis Sativd). The Influence of Plant Growth Regulators on Sex Expression in Male and Female Plants. Acta Soc. Bot. Pol. Pol. Tow. Bot. 2015, 47 (1–2), 153–162.

(11) Manzano, S.; Martínez, C.; García, J. M.; Megías, Z.; Jamilena, M. Involvement of Ethylene in Sex Expression and Female Flower Development in Watermelon (Citrullus Lanatus). Plant Physiol. Biochem. 2014, 85, 96–104.

(12) Iqbal, N.; Khan, N. A.; Ferrante, A.; Trivellini, A.; Francini, A.; Khan, M. I. R. Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones. Front. Plant Sci. 2017, 8, 475.


Created by

Samuel Bonne


Founder @Phantom Ghostwriters

Founder @Phantom Ghostwriters | Biological Chemist | Writer | Psychoactive substances specialist |SEO/digital marketing specialist







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