How to make weed seeds sterile

Development and Standardization of Rapid and Efficient Seed Germination Protocol for Cannabis sativa

Cannabis seed germination is an important process for growers and researchers alike. Many biotechnological applications require a reliable sterile method for seed germination. This protocol outlines a seed germination procedure for Cannabis sativa using a hydrogen peroxide (H2O2) solution as liquid germination media. In this protocol, all three steps including seed sterilization, germination, and seedlings development were carried out in an H2O2 solution of different concentrations; 1% H2O2 solution showed the fastest and the most efficient germination. This protocol also exhibited high germination efficiency for very old cannabis seeds with lower viability. Overall, this protocol demonstrates superior germination compared to water control and reduces the risk of contamination, making it suitable for tissue culture and other sensitive applications.

Keywords: Cannabis sativa, Rapid germination, Hydrogen peroxide, Seed sterilization, Seedling development

Background

Cannabis sativa, otherwise known as marijuana or hemp, is an annual primarily dioecious flowering plant in which male/female sex is determined by heteromorphic chromosomes (X and Y) ( Gaudet et al., 2020 ). Cannabis is grown for a variety of agricultural uses; nearly all parts of cannabis plant are used, seeds for food, stem for fiber, and flowers/leaves for medicine. Flowers produce a mix of cannabinoids and aromatic compounds valued for their therapeutic and recreational effects ( Chandra et al., 2017 ). Cannabis plants are propagated either clonally through cuttings or via seed germination. Seed germination is very important for researchers, breeders, and growers alike, especially since seeds from elite cultivars can be very expensive and valuable. Additionally, older seeds may have a reduced germination rate while bacterial and fungal contamination can compromise germination, especially when seeds are germinated for tissue culture propagation. To address these issues, we have developed a rapid, sterile, and efficient seed germination protocol using a 1% hydrogen peroxide (H2O2) solution. In this protocol, all three steps including seed sterilization, germination, and seedlings development were carried out in a 1% H2O2 solution. This presents a significant advantage over other sterilants, such as mercuric chloride or bleach, which require additional washing of seeds and a separate germination step on MS solid medium. Our protocol resulted in faster germination and increased seed germination percentage as compared to water control, with no bacterial or fungal contamination, making it suitable for tissue culture and other sensitive applications. In comparison to previous germination methods which take between 4-7 days for radicle appearance and 5-15 days for seedling development ( Wielgus et al., 2008 and references therein), our germination method resulted in radicle appearance in 1 day and allowed us to obtain cannabis seedlings in a very short period (3-7 days) with minimal efforts. This protocol is also very efficient for germination of very old cannabis seeds with lower viability.

Materials and Reagents

All seeds were harvested in our laboratory. Blueberry seeds were not older than 6 months, when employed in the experiments. Finola and X59 seeds were more than 5 years old.

Equipment

Growth chamber (Sanyo MLR-350, catalog number: 859-600-06): 24 °C, 18 h light/6 h dark cycle, light intensity 200 μmol·m -2 ·sec -1

Procedure

Seed germination assay

Soak seeds overnight in various concentrations of hydrogen peroxide solution (liquid germination media or germination solutions) as well as in sterile water control (H2O, 1% H2O2, 3% H2O2, 5% H2O2, or 10% H2O2) in 15 or 50 ml screw-cap (Falcon tube). Falcon tubes with submerged seeds in various germination solutions were kept in the dark at room temperature.

Next day, record the percentage of germinated seeds in germination solution (appearance of radicle is considered as germination event) and add fresh respective germination solution after removal of old solution simply by pouring out.

Keep seeds soaked in the same solution for 3 more days in the dark at room temperature and record the percentage of germinated seeds every day.

Thereafter, germinated seeds/seedlings were transferred with or without seed coats from H2O2 solution to MS medium plates to observe the growth of H2O2 solution-germinated seeds/seedlings on MS medium. To transfer, first germinated seeds/seedlings were poured together with H2O2 solution from the Falcon tube to the empty petri plate. Then seedlings were transferred to sterile paper by using forceps to remove excess H2O2 solution. Finally, the germinated seeds/seedlings were transferred to MS media plate by using forceps. The whole transfer process has been carried out in the laminar flow hood.

Parafilm sealed MS medium plates with germinated seeds/seedlings are then transferred to the growth chamber (24 °C, 18 h light/6 h dark cycle and light intensity 200 μmol·m -2 ·sec -1 ) for 3 days to observe the growth and survival of H2O2 solution germinated seeds/seedlings on MS medium.

The H2O2 solution-germinated seeds/seedlings growth was also observed in soil. Pro-Mix HP Mycorrhizae Growing Medium used for soil experiment. The cannabis seeds were soaked in the H2O2 solution (germination solutions) for four days and thereafter, germinated seeds/seedlings were transferred from H2O2 solution to soil pot (Pro-Mix HP Mycorrhizae Growing Medium) to observe the growth and survival of H2O2 solution germinated seeds/seedlings on soil. The soil pots were transferred to the growth chamber (24 °C, 18 h light/6 h dark cycle and light intensity 200 μmol·m -2 ·sec -1 ). The photographs were taken on day 12.

Data analysis

Mean seed germination percentage under various concentrations of H2O2 solution as well as water control were calculated in an excel sheet. Data were shown as mean ± SE.

Results

In this study, we have described a rapid and efficient seed germination protocol for Cannabis sativa. The brief description of this protocol has been reported in Sorokin et al. (2020) . In the current study, we have standardized the optimum concentration of hydrogen peroxide (H2O2) solution media for efficient sterilization and rapid germination. We have tested various concentrations of H2O2 solution as well as sterile water control (H2O, 1% H2O2, 3% H2O2, 5% H2O2, or 10% H2O2) for sterilization and germination efficiency. All three steps of germination (seed sterilization, germination, and seedlings development) were carried out in various concentrations of H2O2 solution and seeds were kept in liquid media for four days. Hydrogen peroxide presents several significant advantages over mercuric chloride or bleach sterilants, which require additional seed washing, and separate germination/seedling development step in Murashige and Skoog (MS) agar medium ( Sorokin et al., 2020 ). The 1% H2O2 solution showed rapid and higher germination than higher H2O2 concentrations solution and water control at day 1 ( Figure 1 ). On day 1, 1% H2O2 solution exhibited 82.5% germination as compared to 22.5% germination for 3% H2O2 group, 17.5% germination for 5% H2O2 group and 47.5% germination in water control group ( Figure 1B ). Interestingly, 10% H2O2 did not show any germination on day 1 due to its toxic effect ( Figure 1 ). In 1% H2O2 solution, radicle appearance (germination) occurred within 24 h and seedling development (two fully developed cotyledons and two immature true leaves stage) occurred in 72-96 h ( Figure 1A ). In comparison to previous germination methods which take between 4-7 days for radicle appearance and 5-15 days for seedling development ( Wielgus et al., 2008 and references therein), our germination method resulted in radicle appearance in 1 day and allowed us to obtain cannabis seedlings in a very short period (3-7 days) with minimal efforts ( Figures 1 -2). Considering the possible toxic effect of H2O2 (since germinated seeds/seedlings stayed continuously in H2O2 solution for 4 days), we have checked further survival of germinated seeds/seedlings on MS media and soil ( Figures 2 -3). On MS media, 1% H2O2 solution seedlings survived better than other treatments ( Figure 2 ). The water germinated seeds exhibited contamination and did not survive on MS media ( Figure 2 ). Similarly, due to the toxic effect of higher concentration of H2O2, the 10% H2O2 germinated seeds did not survive on MS media ( Figure 2 ). The 1% H2O2 solution seedlings also survived well on soil ( Figure 3 ). Apart from this, we have also tested our method for more than 5-years old cannabis seeds with lower viability, which demonstrated that 1% H2O2 solution medium exhibited a very high germination percentage (~50%) as compared to water control (~10%) ( Figure 4 ). In conclusion, we have developed a rapid and efficient method for C. sativa seed germination under sterile conditions for tissue culture and other sensitive applications.

Germination of 6-month-old seeds of Blueberry variety in various concentrations of hydrogen peroxide solution and water control.

A. Representative photographs of germinated seeds/seedlings in the H2O2 solution of various concentrations or water control on day 1 to day 4. B. Comparison of germination percentage between the various concentrations of H2O2 solution or water control. Data are shown as mean ± SE (n = 4). In each replicate, 30 seeds were used.

Representative photographs of growth and survival of H2O2 solutions germinated seeds/seedlings of Blueberry variety on MS media.

The Blueberry variety seeds were soaked in the H2O2 solution (germination solutions) for four days and thereafter, germinated seeds/seedlings were transferred from H2O2 solution to MS medium plates to observe the growth and survival of H2O2 solution germinated seeds/seedlings on MS medium. The photographs were taken at day 0 (just after transfer to MS medium plates), day 1 (after 24 h of the transfer to MS medium plates), and day 3 (after 72 h of the transfer to MS medium plates) on MS media.

Representative photograph of Blueberry variety young plantlet growing in soil (Pro-Mix HP Mycorrhizae Growing Medium).

The Blueberry variety seeds were soaked in the H2O2 solution (germination solutions) for four days and thereafter, germinated seeds/seedlings were transferred from H2O2 solution to soil pot (Pro-Mix HP Mycorrhizae Growing Medium) to observe the growth and survival of H2O2 solution germinated seeds/seedlings on soil. The photographs were taken on day 12.

Germination of 5-years old seeds of Finola and X59 varieties in 1% hydrogen peroxide solution and water control.

Comparison of germination percentage between 1% H2O2 solution media and water control. Data are shown as mean ± SE (n = 5). In each replicate, around 30 seeds were used.

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Recipes

4.43 g Murashige & Skoog Basal Medium with Vitamins

Adjust pH to 5.7 with KOH and sterilize by autoclaving at 121 °C for 40 min. 25 ml of MS media on each Petri plate.

Acknowledgments

This protocol is derived from Sorokin et al. (2020). We thank the Natural Sciences and Engineering Research Council of Canada (NSERC) and MITACS for funding our work.

Competing interests

The authors declare that they have no competing interests.

Citation

Readers should cite both the Bio-protocol article and the original research article where this protocol was used.

References

1. Chandra S., Lata H. and ElSohly M. A.(2017). Cannabis sativa L.-botany and biotechnology. Chandra, S., Lata, H. and ElSohly, M. A.(Eds.). Springer International Publishing: Cham, Switzerland. ISBN: 9783319545639. [Google Scholar]

2. Gaudet D., Yadav N. S., Sorokin A., Bilichak A. and Kovalchuk I.(2020). Development and optimization of a germination assay and long-term storage for Cannabis sativa pollen . Plants 9 : 665. [PMC free article] [PubMed] [Google Scholar]

3. Sorokin A., Yadav N. S., Gaudet D. and Kovalchuk I.(2020). Transient expression of the β-glucuronidase gene in Cannabis sativa varieties . Plant Signal Behav 15 ( 8 ): 1780037. [PMC free article] [PubMed] [Google Scholar]

4. Wielgus K., Luwanska A., Lassocinski W. and Kaczmarek Z.(2008). Estimation of Cannabis sativa L. tissue culture conditions essential for callus induction and plant regeneration . J Nat Fibers 5 : 199-207. [Google Scholar]

Cannabis seeds 101: How to grow marijuana from seed

Cannabis is grown from one of two sources: a seed or a clone. Seeds carry genetic information from two parent plants and can express many different combinations of traits: some from the mother, some from the father, and some traits from both.

In commercial cannabis production, generally, growers will plant many seeds of one strain and choose the best plant. They will then take clones from that individual plant, which allows for consistent genetics for mass production.

If cannabis is legal in your state, you can buy seeds or clones from a local dispensary, or online through various seed banks.

Cannabis seeds vs. clones

For the typical homegrower, it may be easier to obtain cannabis seeds rather than clones. Growing from seed can produce a stronger plant with more solid genetics.

Plants grown from seed can be more hearty as young plants when compared to clones, mainly because seeds have a strong taproot. You can plant seeds directly into an outdoor garden in early spring, even in cool, wet climates.

If growing outside, some growers prefer to germinate seeds inside because they are delicate in the beginning stages of growth. Indoors, you can give weed seedlings supplemental light to help them along, and then transplant them outside when big enough.

Most seeds that you will buy are regular seeds as described above, but here are a couple more types.

How weed seeds work

Cannabis can be either male or female—also called “dioecious”—but only females produce the buds we all know and love. For reproduction, males have pollen sacs and pollinate females, causing female flowers to produce seeds.

Once cannabis seeds are mature, the female plant begins to die, and seeds are either dropped to the ground where they grow into new cannabis plants next spring, or the seeds are harvested for processing into seed oil or food products, or stored so they can be sown in the ground later and become the next generation of plants.

To get the buds found in medical and recreational stores, female cannabis plants are grown in an environment without males—or the males are removed from the area before they release pollen—so the females don’t create seeds. Females can then focus their energies on producing buds and not seeds—this high-potency marijuana is traditionally known as “sinsemilla,” meaning “seedless.”

Some varieties of cannabis can produce male parts alongside female flowers on the same plant, especially if exposed to environmental stressors. These plants are known as hermaphrodites, and sometimes they can self-pollinate to create seeds.

Pros and cons of using cannabis seeds

Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube .

If buying from a reputable breeder or seed bank, growing from seed is the best way to ensure your plants will have solid genetics and start clean, meaning they won’t come with diseases or pests.

Also, buying from a reputable breeder or seed bank will give you a sense of what a particular strain will look and smell like, how it will grow, and how much it will yield at harvest.

The main drawback to growing from seed is there is no guarantee as to what you’ll end up with—if you buy a regular pack of cannabis seeds, it will be a mix of males and females. You’ll need to sex them out (more below) to identify the males and get rid of them, because you don’t want your females producing seeds.

Sexing marijuana plants can be a time-consuming process, and if you don’t catch males, there is a risk that even one males can pollinate your entire crop, causing all of your female weed plants to produce seeds.

One way to avoid sexing plants is to buy feminized seeds (more below), which ensures every seed you plant will be a bud-producing female.

You can also minimize headaches and avoid the hassle of seed germination and sexing plants by starting with clones.

How weed clones work

Aside from producing cannabis through seeds, or sexual reproduction, you can also reproduce the plant through cloning, or asexual reproduction. A clone is a cutting that is genetically identical to the plant it was taken from—that plant is known as the “mother.”

Pros and cons of using cannabis clones

Through cloning, you can create a new harvest with exact replicas of your favorite plant. Because genetics are identical, a clone will give you a plant with the same characteristics as the mother, such as flavor, cannabinoid profile, yield, grow time, etc. So if you come across a specific strain or phenotype you really like, you might want to clone it to reproduce more buds that have the same effects and characteristics.

With cloning, you don’t have to get new seeds every time you want to grow another plant—you just take a cutting of the old plant—and you don’t have to germinate seeds or sex them out and get rid of the males.

One drawback of clones is they need to be taken during the vegetative stage of a plant—flower is too late—so if you have a small setup with only one light, it can be hard to keep clones alive while flowering other plants, because the two need different amounts of light.

Another drawback to clones is they can take on negative traits from the mother plant as well. If the mother has a disease, attracts pests, or grows weak branches, its clones will probably have the same issues.

Additionally, every long-time grower will tell you that clones degrade over time.

What are feminized cannabis seeds?

Feminized cannabis seeds will produce only female plants for getting buds, so there is no need to remove males or worry about female plants getting pollinated. Feminized seeds are produced by causing the monoecious condition in a female cannabis plant—the resulting seeds are nearly identical to the self-pollinated female parent, as only one set of genes is present.

This is sometimes referred to as “cloning by seed” and will not produce any male plants. This is achieved through several methods:

  • By spraying the plant with a solution of colloidal silver, a liquid containing tiny particles of silver
  • Through a method known as rodelization, in which a female plant pushed past maturity can pollinate another female
  • Spraying seeds with gibberellic acid, a hormone that triggers germination (this is much less common)

Most experienced or commercial growers will not use feminized seeds because they only contain one set of genes, and these should never be used for breeding purposes. However, a lot of beginning growers start with feminized seeds because they eliminate the worry of having to deal with male plants.

Top feminized cannabis strain families

A lot of classic weed strains that have been around for a while come in feminized form. Some popular fem seeds are:

  • OG Kush
  • Haze
  • Afghan
  • GSC (Cookies)
  • Skunk
  • Cheese
  • Gelato

What are autoflowering cannabis seeds?

Autoflowering seeds are also popular with beginning growers. They are easy to grow because you don’t have to worry about light cycles and how much light a plant receives.

Most cannabis plants begin flowering when the amount of light they receive on a daily basis reduces. Outdoors, this happens when the sun starts setting earlier in the day as the season turns from summer to autumn. Indoor growers can control when a plant flowers by reducing the daily amount of light plants receive from 18 hours to 12 hours.

However, a type of cannabis called Cannabis ruderalis, which developed in extreme northern conditions without much sunlight, will begin flowering once the plant reaches a certain age—they automatically start flowering regardless of the amount of light they receive, hence the name “autoflower.”

Pros and cons of growing autoflower

Because they grow and flower quicker, growers can fit in multiple autoflower cannabis harvests into the span of one regular harvest.

Autoflowers can be started in early spring and will flower during the longest days of summer, taking advantage of high quality light to get bigger yields. Or, if you get a late start in the growing season, you can start autoflowers in May or June and harvest in the fall.

Also, autoflower plants are small—perfect for closet grows or any small grow, or growing outdoors where you don’t want your neighbors to see what you’re up to.

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A couple big drawbacks, though: Autoflower strains are known for being less potent. Also, because they are small in stature, they usually don’t produce big yields.

However, potency in autoflowering varieties has increased significantly since their initial introduction, with some breeders crossbreeding the low-THC ruderalis with other more potent varieties.

Tips for growing autoflower marijuana seeds

Autoflowering strains require some preparation, as they will grow quickly and start to flower whether or not you’re ready for them.

Climate considerations

Many marijuana growers start autoflowers early in the season, and at a different time than a regular crop, so keep the season and climate in mind when growing and harvesting—your plants still need warmth to grow, and rain can give them bud rot. Consider growing in a greenhouse to protect them.

Training plants

Because training happens during vegetative growth, for autoflowering plants, this period could be as short as a few weeks, which means time is limited. Try topping your autoflowers after they have three nodes, and stop once they begin to flower. You will want to prune them lightly.

Go easy on nutrients

Autoflowers don’t need lots of nutrients because they’re small and don’t spend much time in the vegetative cycle. They won’t need as much veg nutrients—such as nitrogen—but will need more bloom nutrients.

What are high-CBD cannabis seeds?

CBD, or cannabidiol, is one of the chemical components—known collectively as cannabinoids—found in the cannabis plant. Over the years, humans have selected plants for high-THC content, making cannabis with high levels of CBD rare. The genetic pathways through which THC is synthesized by the plant are different than those for CBD production.

Cannabis used for hemp production has been selected for other traits, including a low THC content, so as to comply with the 2018 Farm Bill. Consequently, many varieties of hemp produce significant quantities of CBD.

As interest in CBD as a medicine has grown, many breeders have crossed high-CBD hemp with cannabis. These strains have little or no THC, 1:1 ratios of THC and CBD, or some have a high-THC content along with significant amounts of CBD (3% or more).

Seeds for these varieties are now widely available online and through dispensaries. It should be noted, however, that any plant grown from these seeds is not guaranteed to produce high levels of CBD, as it takes many years to create a seed line that produces consistent results. A grower looking to produce cannabis with a certain THC to CBD ratio will need to grow from a tested and proven clone or seed.

How to germinate marijuana seeds

Germination is the process in which a seed sprouts and begins to grow into a new plant. Also referred to as “popping,” germination is the very first step in starting your weed grow.

Marijuana seeds can be acquired from an array of sources and can vary in quality. For more info on how to buy marijuana seeds, check out our Guide to buying cannabis seeds.

Cannabis seeds require three things to germinate: water, heat, and air. There are many methods to germinate seeds, but for the most common and simplest method, you will need:

  • Two clean plates
  • Four paper towels
  • Seeds
  • Distilled water

Step 1

Take four sheets of paper towels and soak them with distilled water. The towels should be soaked but shouldn’t have excess water running off.

Step 2

Take two of the paper towels and place them on a plate. Then, place the marijuana seeds at least an inch apart from each other and cover them with the remaining two water-soaked paper towels.

Step 3

To create a dark, protected space, take another plate and flip it over to cover the seeds, like a dome.

Step 4

Make sure the area the seeds are in is warm, somewhere between 70-85°F.

After completing these steps, it’s time to wait. Check the paper towels once a day to make sure they’re still saturated, and if they are losing moisture, apply more water to keep the seeds happy.

Some seeds germinate very rapidly while others can take a while, but generally, seeds should germinate in 3-10 days. If it’s been two weeks and a seed hasn’t sprouted, it’s probably a dud and won’t sprout.

A seed has germinated once the seed splits and a single sprout appears. The sprout is the taproot, which will become the main stem of the plant, and seeing it is a sign of successful germination.

It’s important to keep the delicate seed sterile, so don’t touch the seed or taproot as it begins to split.

Transplanting germinated cannabis seeds

Once you see the taproot, it’s time to transfer your germinated seed into its growing medium, such as soil.

  • Fill a 4-inch or one-gallon pot with loose, airy potting soil
  • Water the soil before you put the seed in; it should be wet but not drenched
  • Poke a hole in the soil with a pen or pencil—the rule of thumb is: make the hole twice as deep as the seed is wide
  • Using a pair of tweezers, gently place the seed in the hole with the taproot facing down
  • Lightly cover it with soil

Keep a close eye on the temperature and moisture level of the soil to keep the seed happy. It’s very delicate at this stage. Use a spray bottle to water it—over-watering can suffocate and kill the delicate sprout.

Within a week or so you should see a seedling begin to grow from the soil.

Germinating cannabis seeds doesn’t always go as planned. Some seeds will be duds. Others will be slow and take longer to sprout. But some will pop quickly and grow rapidly.

This is the beauty of seeds—often, you can tell which plants or genetics will thrive right from the get-go. This will help you determine which plants you want to take cuttings from for clones or for breeding if you want to create a seed bank of your own.

How to sex a pot plant

Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube .

As we’ve mentioned, cannabis is a dioecious plant, meaning male and female reproductive organs appear on different plants.

Because only female cannabis plants produce buds and you want them to focus all their energy on producing buds and not seeds, it’s important to identify and get rid of male weed plants so they don’t pollinate females. If females are pollinated, it will give you buds filled with seeds, making your weed harsh and unpleasant.

Cultivating males is important for breeders trying to cross new strains and genetics, but most people growing for buds will want to remove the males.

As mentioned above, you can skip the processing of sexing weed plants by growing with feminized seeds or clones.

If growing male and female cannabis seeds, they’ll start to show their sex organs, or “pre-flowers,” after 8-10 weeks from germination.

Cannabis plant sex organs appear on nodes, the points where branches grow off from the main stalk.

Males will have round balls—these will develop into pollen sacs, which will release pollen into the air when mature.

Females will have a round structure with long hairs—these hairs will develop into pistils, which will catch pollen in the air.

Pre-flowers can initially be extremely small and hard to identify with the naked eye, but you can use a magnifying glass to get a better look.

Can I grow a seed I found in a bag of weed?

Finding a cannabis seed in your stash is not ideal, but we’ve all been there before. Although much less common than it once was, it still happens. Sometimes you’ll notice one when grinding down some flower, or you’ll see one pop, spark, and crackle from the heat of a lit bowl.

These are referred to as “bagseeds” and whether or not you can grow one will depend on where it came from.

Is a bagseed good or bad?

Seeds found in finished cannabis buds can develop for a number of reasons. For example, a male plant may have accidentally pollinated a flowering female during the growing process. But more commonly, they’re a sign of stress and can be attributed to high temperatures during the final stages of flowering or an exaggerated spike in climate or environment.

Seeds can also form in plants with genetic disorders or instability, like hermaphrodites—plants that develop both male and female reproductive parts. Generally, stress and genetic disorders are viewed as bad, so temper expectations with any plant you start from a bagseed.

But sometimes you get lucky and find a mature seed in some really nice herb. Strains like the legendary Chemdog wouldn’t be possible without adventurous smokers planting and proliferating the seeds they found in a bag of kind bud.

So don’t discount bud because it has a seed or two in it. While not ideal, it could be the origins of the next great weed strain.

Ask yourself a few questions to decide if it’s worth the time and energy to grow the seed.

Was the seed found in good weed?

If you don’t like the flavor, effects, or even the look of the bud, then it’s probably not worth growing.

Are you ready to grow?

Growing marijuana takes a certain level of commitment: time, energy, and financial resources, so be sure you can commit to the whole process.

Is the seed viable?

For a seed to be viable, it must be mature enough to have a completely formed genetic blueprint, and it must be strong enough to germinate and pop through its hard casing and sprout its crucial taproot.

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There are a few indicators that will give you a sense of whether the seed is worth germinating.

  • Tiger stripes—dark stripes on the seed which resemble veins on a leaf are generally good
  • Solid shell—a seed should be able to withstand a little pressure when pinched between your fingers; if it crumbles or cracks, it’s no good

Immature seeds tend to be light in color and have a soft outer shell.

In some cases, even if a seed isn’t completely mature, there’s still a chance it could be viable. But often these are extremely weak, take long to develop, and express other unfavorable characteristics. Growers usually discard weak plants to free up space.

You might also find a mature seed that has been physically damaged through poor handling, like rough trimming. In those cases, it probably isn’t worth the effort to try and germinate the seed.

But if the seed you found looks decent, you might as well germinate it and see what sprouts.

Time to germinate

Viable or not, there’s only one sure way to find out if a bagseed will grow. If you’re simply curious to learn and not as concerned with the overall outcome, you can plant a couple of bagseeds outside and see what happens.

If you’re ready for a more serious approach, make sure you have the space for a proper garden and pop the seeds to see what fruit they bear.

Even if your seed sprouts fast and grows vigorously, it still has roughly a 50/50 chance of being female and producing buds, instead of turning out to be a male.

Remember, once a seed germinates, the real work begins. Sexing, selecting, vegetative growth, flowering, and the eventual harvest all lie ahead.

How to buy cannabis seeds

Cannabis seeds can be found on numerous online seed banks, but note that it is illegal to bring seeds into the US and Customs will seize any cannabis seeds that they find in packages or on a person. In legal and medical states, you may purchase seeds at a dispensary.

Sterile Cannabis Plants?

First of all, I must admit that searching for information on sterile plants is hard and there is almost no scientific information on sterile or infertile cannabis. But I managed to find something and I think this is enough to educate anyone on what is this strange phenomenon and how can it help us.

If you know anything more about this strange sterile phenomenon then feel free to leave a comment!

What are sterile plants?

Sterile cannabis plants are female or male plants that can’t reproduce or in other words, females can’t create seeds and cannot be pollinated while the pollen on sterile males cannot pollinate any females or their pollen sacks just doesn’t create any pollen.

Why are they that way?

Sterile plants are that way because they have some sort of genetic anomaly. This genetic anomaly doesn’t produce pollen or produces pollen that is not in the right size or shape in male plants but produces short female pollen tubes or misshaped tubes in female flowers.

This genetic sterility can express itself through natural mutation or can also be induced chemically and is used for many different plant species in feminized seed and female-only plant production.

But what about cannabis? Are cannabis plants also sterile and how can this help us?

From the information I managed to find, there is no scientific research on male or female sterility but there are however some forum threads where people say they have sterile plants. And this should be true because cannabis is just like any other plant and if other plant species can become sterile then why can’t marijuana.

You now probably ask yourself how this sterility expresses itself and where does it come from. Well if a male plant would be sterile then in theory it either:

Should not produce any male flowers at all.

Should produce immature or misshaped pollen sacks.

should produce pollen that is in the wrong shape and is not viable.

If any of these three variations can actually be true then this male sterility can become a real deal-breaker for seedless gardens and sterile seeds as you could get infertile male plants that could not pollinate your precious females.

But if a female cannabis plant should become sterile it could have misshaped calyxes or no pollen tubes at all, but they can also have some anomaly that they can take in that male pollen but does not produce seeds. This female sterility would be a miracle for seedless crop production as no pollen could ever ruin your garden and even hermaphrodite plants would not damage your overall yield. As for the question where does these sterile plants come from, I found that there are natural mutations in plants but they are really rare but some growers have experimented with chemicals that create these sterile cannabis plants.

In the information I managed to pull up there were some guys saying that their females were not pollinated by male pollen even if other strains did get pollinated and this could be female sterility!

In another place I found a grower saying that his male pollen did not pollinate any female plants and that was strange to him because he applied the pollen directly over the female flowers so in this case, it could be that male plant infertility.

There was another forum thread where a grower told that he got seeds but none of them sprouted and this could have been attributed to immature seeds or maybe those seeds were in fact sterile like the terminator seeds that Monsanto wanted to use on other commercial crops.

After examining these few cases I can’t be completely sure whether some or all of them had some variation of these sterile cannabis plants/seeds. But this could be a major turning point for large seed breeders if they manage to find and perfect this technology as then we could have no chance of getting seeds in our garden and we could grow clean and beautiful buds.

On the other hand, if large-scale seed breeders would introduce these sterile seeds we would not be able to breed our own strains and if they would not supply regular seeds there would be no breeding at all!

Can there be sterile offspring from feminized seeds?

I found a lot of talk about feminized seeds and that they produce seeds that do not germinate or they themselves produce hermaphrodites that have pollen that is non-viable. I don’t know if this statement is true but from my own experience, I can say that feminized cannabis plants can be pollinated and can produce seeds so I don’t know where this information is coming from.

I have also found many forums posts where growers are saying they have bread feminized seeds and got viable beans so this myth is busted at least till someone provides some solid evidence of those sterile offspring.

Does tetraploid crossing produce sterile seeds?

This is the only way that I have found that allows us to produce sterile plants and it is the process that creates those terminator seeds.

Basically what you need to do is treat a normal cannabis plant with a chemical called “colchicine” that induces cells to give off twice as many chromosomes and leaves other cells with no chromosomes. These plants that have been treated with this chemical then grow much much stronger and bigger than regular diploid ones.

They are called Tetraploids because they have double the number of chromosomes and it is speculated that in the 70s and 80s growers were experimenting with these chemicals and that many of today’s commercial high yielding strains have these genetically modified parents in their lineage.

But what is interesting when talking about these sterile plants is that if this tetraploid cannabis plant is crossed with diploid (normal plant) it gives off an offspring that is a triploid and because it has an odd number of chromosomes it can’t produce offspring!

Because this method is so efficient it is used in commercial crops to create seedless fruits or infertile male plants and I think there could be a potential to use this technology in cannabis as well!

Dutch Master Reverse

This is a very interesting product that I found and it supposedly should kill off all the male pollen sacks on a hermaphrodite cannabis plant.

I read that it is no longer sold in the US because of some studies suggesting it could be harmful if ingested so I am not willing to use it on my plants but the fact that it doesn’t let male flowers to produce is another sign that there can be a sterile cannabis plant and we just need to do some more experimentation.

As you can see there are some methods that alter cannabis plant sex and could potentially produce sterile or infertile cannabis seeds and if someone figures it all out we could grow plants that would be 100% female and with the process of cloning you could potentially get a garden that does not produce hermaphrodites and if it does they would not have viable pollen.

The last thing that popped in my mind was that sterile seeds and autoflowers could also go hand in hand as today’s feminized autoflowering varieties are sometimes producing hermaphrodites that pollinate your garden but with this sterile plant technology this could be avoided but you would need to buy new seeds for every grow!

Here are the resources I used and there are also those forums that I mentioned so if you are interested check them out and leave a comment here about your findings!