Seeds in female weed plant

I have an indoor growroom and in my recent harvest I found seeds in the buds, but I’m sure there are no male plants in the room. I’ve heard that light leakage can cause plants to become hermaphrodites. Is this true, and if so, do you have any tips for avoiding this?

Cannabis plants are monecious. This means they have the ability to be either male or female. Or in the case of hermaphroditism, they can be both. The reason to make sure there are no males or hermaphrodites in your garden is because male flowers make pollen. When pollen touches the white hairs on a flower, it makes a seed, and seeded weed gives you headaches. Even though there are reasons in nature hermaphroditism could be important, such as continuing the species in case there is no male present, hermaphroditism is generally a bad thing when talking about cannabis plants.

Light poisoning is the most common cause for a normal plant to hermaphrodite.

Light poisoning refers to the flowering night cycle of a plant being unnaturally interrupted with light. The best way to prevent this is to close yourself inside your darkened room during the daylight, and then after allowing a few minutes for your eyes to adjust to the dark, check for any light leaks from covered windows, door jams, etc. Also cover all timer and appliance lights with tape.

Negative stressors can combine with small interruptions of the light cycle to cause hermaphroditism, especially with less-stable, clone-only hybridized strains. When the night cycle is abnormally interrupted, it sends a mixed hormonal signal to the plant. This can cause a full female plant to throw some male flowers. Male flowers are easy to identify, especially when side by side with female flowers. Male flowers look like small bunches of bananas, which will take a week or two to swell before they burst and release their pollen.

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Finding a hermaphrodite in your growroom can happen at any stage of the flowering cycle and is indicated by the presence of male flowers growing on the same plant as female flowers. As with all species in nature this can occur in varying degrees. A plant can become slightly or majorly hermaphroditic. In cases where singular male flowers are found between the branch and stalk nodes, you should be diligently removing them as they grow. You must re-inspect the plant top to bottom every few days to be sure pollination and seeding doesn’t occur. If you find male flowers (anthers) actually growing from within the female flowers (buds) the situation is a little more dire. You can still remove all the male anatomy as it appears, but it will be harder to find and much more prevalent. This is a horrible discovery that leads to a tough decision: Should you let the plant live and risk the whole crop being ruined by seeds?

In either case, once hermaphroditism has compromised the safety and purity of your sensimilla, the plant should not be propagated further. Remember, once a hermy, always a hermy. The plant pictured here is in the tenth and what should have been the final week of ripening, but a timer failed and one light stayed on continuously for almost two weeks, causing this vegetative regrowth. Because the light was continuous, the plant made no pollen. This method of re-vegging can be used to save a flowering plant you have no copies of, but be careful, as this may cause some strains to hermaphrodite.

Purposefully causing a plant to hermaphrodite is called selfing. Gibberellic acid or colloidal silver is typically sprayed onto the female plant. This technique is used to make feminized seeds and uses the plant’s ability to be both male and female to force a female plant to produce male flowers. The pollen contained in these male flowers can only produce female seeds. Just keep in mind that feminized plants should not be used for breeding, as they were produced without a true male, making them genetically inferior.

Marijuana plant anatomy

The cannabis plant has several structures, many of which we can find on any ordinary flowering plant species. Cannabis grows on long skinny stems with its large, iconic fan leaves extending out from areas called nodes.

Cannabis really stands out in its flowers—or buds—where unique and intricate formations occur: fiery orange hairs, sugary crystals, and chunky buds enveloped by tiny leaves.

Parts of the cannabis plant

Seeds

Seeds are produced in female cannabis plants and carry the genetics of a male and female. Seeds need to germinate to sprout and will grow a taproot, which will become the main root that anchors the plant.

Cotyledon leaves

These are the first leaves to grow from the seed after germination. They usually come in pairs, and seeing them is a sign of successful germination and that your plant is on its way to growing healthy and strong.

Roots

The roots grow down from the main stalk of the plant into the soil. When growing from a seed, the main root is called the “taproot.” Roots are the lifelines of a cannabis plant, pulling water and oxygen into the plant so it can grow healthy and strong.

Mycorrhizae, a beneficial fungus, can be added to soil to improve root systems.

The main stem, or stalk, of a cannabis plant grows straight up from the root system and supports all lateral branches. The stem gives a plant structure and stability.

Often, growers will top, or cut off, the stem after about five nodes, which forces the plant to grow out laterally more, creating more bud sites.

Branches

Branches grow out of the main stem and support fan leaves and buds. Growers often train a cannabis plant by topping branches to create more bud sites.

A node is a point at which a branch grows off of the main stem, or one branch from another branch. Fan leaves and buds can grow on some nodes, but not necessarily all.

When determining the sex of a cannabis plant, pre-flowers, or the beginnings of male and female sex organs, will appear at the nodes.

The space between nodes is called “internodal spacing” and will give you a sense of whether a plant will grow tall or short.

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

Fan leaves

Fan leaves are the large, iconic leaves of the cannabis plant. They capture light for the plant and typically have little-to-no resin and are usually discarded when trimming.

Sugar leaves

Sugar leaves are the small, resin-coated leaves that buds form around. Sugar leaves are usually saved as “trim” during harvest and can be used for pre-rolls, extracts, and other cannabis products.

Flowers

Also known as “buds,” the flowers of a cannabis plant are the fruits of your labor. They contain the cannabinoids and terpenes that get you high or offer health benefits. Flowers only grow on female cannabis plants and must be dried before consumption.

A cola, also called a “bud site,” refers to a cluster of buds that grow tightly together. While smaller colas occur along the budding sites of lower branches, the main cola—sometimes called the apical bud—forms at the top of the plant.

Bract and calyx

A bract is what encapsulates the female’s reproductive parts. They appear as green tear-shaped “leaves,” and are heavily covered in resin glands which produce the highest concentration of cannabinoids of all plant parts.

Enclosed by these bracts and imperceptible to the naked eye, the calyx refers to a translucent layer over the ovule at a flower’s base.

Stigma and pistil

The pistil contains the reproductive parts of a flower, and the vibrant, hair-like strands of the pistil are called stigmas. Stigmas serve to collect pollen from males.

The stigmas of the pistil begin with a white coloration and progressively darken to yellow, orange, red, or brown over the course of the plant’s maturation. They play an important role in reproduction, but stigmas bring very little to the flower’s potency and taste.

Trichomes

Despite their minute size, it’s hard to miss the blanket of crystal resin on a cannabis bud. This resin is secreted through translucent, mushroom-shaped glands on the leaves, stems, and calyxes.

Plants originally developed trichomes to protect against predators and the elements. These clear bulbous globes ooze aromatic oils called terpenes as well as therapeutic cannabinoids like THC and CBD. The basis of hash production depends on these trichomes and their potent sugar-like resin.

Male vs. female marijuana plants

Cannabis is a dioecious plant, meaning it can be male or female, and the male and female reproductive organs appear on different plants. What’s in your stash jar now are the flowers of a female marijuana plant.

Female plants produce the resin-secreting flower that is trimmed down into the buds you smoke, and males produce pollen sacs near the base of the leaves. Male plants pollinate females to initiate seed production, but the buds we consume come from seedless female plants—these are called “sinsemilla,” meaning “seedless.”

Growers can ensure the sex of their plants by growing clones or the genetically identical clippings from a parent strain. Feminized seeds are also made available through a special breeding process.

How to determine the sex of a marijuana plant

Cannabis plants show their sex by what grows in between their nodes, where leaves and branches extend from the stalk. Pollen sacs will develop on a male plant to spread seeds and stigma will develop on a female to catch pollen. You can see these differences weeks before they actually start serving their purposes in the reproduction cycle. These are known as “pre-flowers.”

Pre-flowers begin to develop four weeks into growth, but they may take a little longer depending on how quickly the sprouting phase occurs. By the sixth week, you should be able to find the pre-flowers and confidently determine the sex of your plant.

Examine the nodes of the plant and look for either the early growth of small sacs on a male, or two bracts on a female, which will eventually produce the hair-like stigma.

Female marijuana plants

Females are the prizes of cannabis plants—they are the ones that grow the buds that we all know and love. Anytime you see a picture of a cannabis plant with buds, you are looking at a female plant.

Female cannabis plants receive pollen from males to produce seeds, which will carry on the genetics of both plants to the next generation.

However, cannabis is primarily cultivated for buds, not seeds, so the practice of growing sinsemilla, or “seedless” cannabis, is prevalent today: Females and males are grown separately, or males are even discarded, to prevent pollination. This allows female plants to focus their energies on bud production instead of seed production.

Males and females are usually only pollinated when crossbreeding plants or creating new strains.

Male marijuana plants

Male cannabis plants grow pollen sacs instead of buds. Male plants are usually discarded because you don’t want them to pollinate the females, which will produce seeds—no one wants to smoke buds with seeds in it.

Males are important in the breeding process, but that is generally best left to expert breeders. When pollinating females, males provide half of the genetic makeup inherited by seeds.

Because of this, it’s important to look into the genetics of the male plants. Their shape, rate of growth, pest and mold resistance, and climate resilience can all be passed on to increase the quality of future generations.

Male plants can also be used for:

  • Hemp fiber—males produce a softer material, while females produce a coarser, stronger fiber. The soft fiber from males is more desirable for products like clothing, tablecloths, and other household items.
  • Concentrate production—males do have some THC and can be psychoactive, but much less so than females. Small amounts of cannabinoids can be found in the leaves, stems, and sacs, which can be extracted to produce hash and other oils.

What are hermaphrodite cannabis plants?

The rare hermaphroditic plant contains both female and male sex organs. These plants can sometimes self-pollinate, but this is typically bad as it will create buds with seeds and also pass on hermaphroditic genes.

“Herming out,” as some call it, is something that generally happens when a plant becomes excessively stressed. Some stressors include:

  • Plant damage
  • Bad weather
  • Disease

There are two types of hermaphrodite plants:

  • A plant that develops both buds and pollen sacs
  • A plant that produces anthers, commonly referred to as “bananas” due to their appearance

While both result in pollen production, true hermaphrodite cannabis plants produce sacs that need to rupture; anthers are exposed, pollen-producing stamen.

Because this occurs when cannabis is under stress, it’s important to monitor plants after they have been exposed to stressors: indoors, high temperatures or light leaks are often the cause; outdoors, a snapped branch might be repaired and then turn into a hermaphrodite.

The other primary cause of hermaphrodite plants lies in its genetics—a plant with poor genetics or a history of hermaphroditic development should be avoided to protect your garden. If you notice any pollen sacs or anthers at any point, remove the plant from your garden immediately to prevent pollination of female plants.

Do Feminized Cannabis Seeds Make Hermies?

What Are Feminized Cannabis Seeds? These seeds all grow up to be female plants. That means every plant produces buds. With “regular” or unfeminized seeds, about half the plants will turn out to be male, which don’t produce buds. They can also pollinate your female plants (causing seedy buds). Therefore most growers will remove male plants from the grow room as soon as they’re identified. Learn more about male vs female plants. Feminized seeds let you plan your grow more effectively because you don’t have to throw half the plants away once they start flowering.

Every plant grown from feminized seeds will produce the buds we know and love. This plant was grown from feminized Swiss Cheese seeds.

What Are Hermies? “Hermie” is short for “hermaphrodite.” Hermie cannabis plants usually look like normal female plants for the most part, but they also grow some male parts that produce pollen. This causes seedy buds just like pollen from male plants. Hermies are to be avoided! Read the full tutorial on hermies.

It’s no good if your “female” plants start growing male flowers or parts of male flowers. That can cause seedy buds just like a male plant!

This bud got completely seeded due to a hermie in the grow space. Notice the lumpy round bits. Those are seeds forming.

What’s the matter with a few seeds?

Cannabis growers are trying to grow sinsemilla (seedless buds). A few seeds won’t hurt anything. But if you have very seedy buds, it significantly lowers your yields because plants are putting all their energy into making seeds. The buds also tend to be less potent if they are full of seeds. Seeds are not the end of the world, but it’s good to avoid if possible.

“Sinsemilla” means “no seeds.” Sinsemilla is the highest quality and most potent of all buds

Since most growers are trying to grow sinsemilla, having only 100% female plants in the flowering grow room is crucial to prevent pollination.

Feminized cannabis seeds can be a blessing for small-scale growers. While male plants produce pollen sacs, feminized seeds ensure all your plants will end up being bud-bearing females (instead of growing half male and half female plants like with regular seeds).

If you don’t have room for extra plants, feminized seeds can make planning your grow a lot easier!

Good feminized seeds should produce only 100% female plants, with no hermies or male plants. So starting with feminized cannabis seeds lets you make the most efficient use of your grow space. You don’t have to worry about identifying male plants and throwing them away before they pollinate your female plants. With good feminized seeds, you know that if you’re growing 10 plants, all 10 of them will make buds, and that makes it easier to plan out your grow ahead of time.

With all these bonuses, why would any small-scale grower use any other type of seeds?

Pros of Feminized Cannabis Seeds

All plants produce buds

You don’t have to throw away half your plants after nurturing them for weeks

You don’t have to worry about your buds getting pollinated, causing seedy buds, reduced bud quality and lower yields

But is there a dark side to feminized cannabis seeds?

One of the biggest worries growers have about feminized seeds is that they will produce hermies instead of 100% female plants as advertised.

This hermie is growing both male and female flowers. Can this be caused by feminized seeds?

Unfortunately, hermies can be a lot easier to miss than a male plant since it may just be a small part of the plant that’s affected. A male plant makes itself known at the beginning of the flowering stage, but a hermie plant may grow only buds except for just one or two tiny pollen sacs. A few yellow hermie bananas hidden in the buds can also produce pollen. Any type of male flower part that grows in your garden can add seeds to your buds, and hermies are some of the worst offenders.

This grower didn’t notice that the buds had been seeded until harvest. As he was trimming, he noticed seeds popping out. Since there were no male plants, chances are this was caused by an unnoticed hermie somewhere in the grow space.

Is it True that Feminized Seeds Sometimes Cause Hermies? Yes!

Many growers believe that feminized seeds can cause hermies, and there is some truth to that. In order to create a feminized seed, one of the parent female plants had to be forced in some way to produce pollen.

That pollen is used to pollinate another female plant, and the offspring of those two plants will all be female since both of the parents were female. That’s how you get feminized cannabis seeds. But that also means every time you have a feminized seed, that seed had a plant that produced male flowers in its recent genetic history.

There are different ways to feminize seeds, but only some methods produce seeds that turn hermie on you.

It’s important to understand that hermies can happen a couple of different ways. And the different types of hermies affect what genes are being passed on to the seeds.

This swollen calyx has a seed developing inside

What Causes Hermies?

Hermies can be caused by many things, including…

bad genetics – the plant comes from a line of plants that naturally create hermies for no reason, even in good growing conditions

high stress – high temperatures, light leaks, inconsistent light schedules, as well as other types of major stress can cause a healthy plant to hermie, though some plants/strains are more susceptible than others

letting buds over-mature – this is also known as “rodelization;” basically when the plant’s buds have gone past maturity without being pollinated (if the grower waits way too long to harvest), a female plant may make male pollen within its buds as a last ditch effort to pollinate itself and make seeds for the next generation

chemical stimulation – by exposing a female plant to certain substances like colloidal silver or gibberellic acid during the early parts of the flowering stage, you can force any female plant to create pollen. This is how seedbanks get female pollen to produce feminized seeds.

Seeds created from “female” pollen will turn out being female (or at least as female as the parents).

The pollen from a hermie plant makes feminized seeds

The pollen sacs on this masculinized female plant have opened and pollen has spilled onto the leaf below

Another type of hermie: a yellow “banana” can appear in your buds and make pollen. This male flower part would normally be inside a pollen sac. When it’s in the open like this, it becomes a little pollen generator.

Feminized seeds are susceptible to becoming hermies themselves when exposed to the same conditions as their female “father” who produced the pollen. But since any plant can be chemically induced to produce pollen, it doesn’t mean that the ability to hermie in a natural environment is passed on to the seeds.

So only some feminized seeds come from parents with bad genetics, and that’s what’s the grower cares about most.

The bagseed gamble… When you find seeds in your buds, that usually means that the buds were pollinated by accident. Seeds that were accidentally created are suspect. It could be that a stray male plant caused them, which means there were no hermies and you will get about half male and half female plants. But accidental seeds could also be the result of herming by an indiscriminate grower, and that means you have feminized seeds, sort of. Some of them may produce pollen on you just like their parents. Growing with bagseed is a big gamble… you never know what you’re going to get.

Are your cannabis bagseeds viable? Viable, good seeds usually appear either dark and striped or solid gray/beige.

If a seed is pure white it usually means it’s underdeveloped and won’t sprout. But it can sometimes be hard to tell. In the end, if a seed sprouts and grows it’s a viable seed! I’ve had very pale, flimsy seeds sprout into gorgeous fast-growing plants, so if you’re not sure the best thing to do is try to germinate it!

Seed Banks & Breeders

Commercial breeders and seed banks use chemical stimulation to create feminized seeds. What that means is they put specific compounds on developing female plants to force them to produce pollen. You can actually do this yourself at home.

This technique works on nearly any female plant, including plants that would never hermie naturally. So it can be used to take two plants with great genetics to produce female seeds. But the same process will also work incredibly well on plants that do hermie easily all on their own. That means it’s up to the breeder to test and make sure that they have a solid plant with unbeatable genetics before using the feminization technique.

The pollen that results from chemical stimulation is used to pollinate another female plant and make feminized seeds. If the parent plants would never hermie without chemical stimulation, then you have created feminized seeds that won’t ever make pollen in your grow room.

But if one of the parent plants was chosen because it does hermie easily, you’ll end up with seeds that likely will herm. The breeder might not have done any testing on the parents or the resulting offspring to even know.

Without testing, a breeder can’t tell whether they’ve created quality feminized seeds

Choosing the Right Cannabis Breeder

Unfortunately, some cannabis seed breeders are more trustworthy than others. The great ones have created stabilized strains that have been bred over several generations to produce a consistent product without any problems with plant sex.

Less scrupulous breeders might breed two random female plants together and sell the resulting seeds as a new strain without any testing. In this second case, you don’t know what to expect, and neither does the breeder.

If the breeder hasn’t tested their strains extensively in many situations, they won’t know whether their seeds tend to hermie or not. If they have carelessly bred plants that have a tendency to herm, then it’s really likely that at least some of the resulting seeds will have the same problem.

Breeder choice is important!

I have to admit I may be biased towards feminized seeds. I’ve grown almost exclusively with feminized seeds over the last decade. It has made my life so much easier! I only purchase seeds from breeders that I trust and all the resulting seeds have been bud-bearing females. I haven’t had any real problems with hermies.

On the flip side, I’ve heard of growers buying feminized seeds from untrustworthy breeders and having a big portion of their seeds turn male or become hermies even in perfect growing conditions. So there is truth to the fact that you can run into hermie problems with feminized seeds.

Yet there are good and bad breeders out there, and with good breeders, you have a very low chance of running into cannabis sex problems.

So if you do choose to purchase feminized seeds (or any seeds really), please make sure you get them from a trusted breeder!

Conclusion: Feminized seeds from a trustworthy breeder have a low chance of producing hermies, but the odds are much worse with feminized seeds from an untrustworthy source

The truth is it takes a hermie of some sort to create feminized seeds. That means that you always run the risk of running into hermies when growing feminized seeds… yet that is true for non-feminized cannabis seeds, too! Lots of regular seeds produce hermies.

What’s most important, whether you get feminized seeds or not, is to get your seeds from a breeder who has a reputation for producing quality genetics. That is the best thing you can do for any strain to ensure a smooth grow. With a great breeder, you have a very low risk of running into any sex or gender problems.

I personally prefer feminized seeds, and that’s the only type of seed I grow. It makes it easier for me in my limited grow space. I haven’t run into any significant problems with hermies, so I’m satisfied with growing only bud-bearing plants.

Yet a lot of growers grow with regular seeds because they’re easier to breed and produce at home. Many growers have created a system for weeding out male plants that is more convenient for them than using feminized seeds.

In the end, when it comes to feminized cannabis seeds you need to decide whether the small chance for hermies is worth the convenience of all-female plants. It’s up to you to figure out what’s best for your needs!