Herming: How female plants turn male Cannabis plants are gendered, or for the botanically-inclined, dioecious. Female plants are particularly prized because they form buds that are rich in Just like humans, cannabis and hemp plants are considered dioecious, meaning they have either male or female reproductive organs. Depending on the goal of the Cannabis plants can be male, female, or hermaphrodites. Knowing the difference can make or break your cannabis operation. Find out their differences inside!
Herming: How female plants turn male
Cannabis plants are gendered, or for the botanically-inclined, dioecious. Female plants are particularly prized because they form buds that are rich in cannabinoid content. For most growers, maintaining a crop free of male plants is critical to ensuring that female buds are not pollinated.
Like all plants, however, cannabis has an inherent drive to procreate by propagating seeds. One way that the plant achieves this is by herming, when female plants become hermaphrodite to self-pollinate. The tendency to herm means that growers must take extra care to minimize any stressors that may cause the plant to perceive a threat and change its sex.
What is herming, and why does it happen?
Herming can occur when female plants experience conditions of environmental stress. “Female plants don’t actually turn male, they become hermaphrodites,” says Bruce Perlowin , CEO of Hemp, Inc . and seasoned cannabis cultivator. “You have a female plant that develops both reproductive parts so it can pollinate itself.” A hermaphroditic plant, by definition, contains both female and male sex organs .
A hermaphroditic plant, by definition, contains both female and male sex organs. Photo by: Gina Coleman/Weedmaps
According to Perlowin, stress is the fundamental cause of hermaphroditic plants, or ‘hermies.’ “Some examples of stressors would be not enough water, too much water, not enough nutrients, or too much heat. It can happen at any time in the life cycle of a plant from a new plant to a very mature one,” explains Perlowin. The female plant will develop male flowers in response to stress, to ensure seeds are produced before the environmental trigger can kill the plant.
Other stressors that may incite female cannabis plants to become hermaphroditic include disruptions to the photoperiod, dramatic shifts in temperature, disease or pest infestations, the use of toxic pesticides, and physical damage from vigorous pruning.
Herming can also have a genetic component, with some growers viewing plants that are inclined to herm as genetically inferior.
“Herming can also definitely be a genetic problem, but it is not cultivar-specific,” says Perlowin. “You can get the same cultivars from different seed companies, and they will yield different results.” Reputable breeders are more likely to competently sort and select seeds from genetically robust plants with desirable traits.
How can growers prevent hermaphroditic plants?
The vast majority of cannabis growers cultivate the plant to produce sensimilla . Sensimilla refers to female cannabis buds that have not been pollinated by a male cannabis plant. Sensimilla is more potent than seeded cannabis as it contains greater concentrations of essential oils and psychoactive cannabinoids.
When female plants herm, or develop male flowers capable of disseminating pollen, the entire crop is at risk of pollination. Female flowers that have been fertilized by pollen will halt their development to produce seeds, limiting flower production.
Perlowin advises that growers who wish to prevent female cannabis plants from herming must be diligent throughout the plant’s grow cycle. For starters, purchase seeds from a reputable company or trustworthy breeder that understands cannabis genetics. While potential environmental stressors must be monitored and minimized, growers should also examine their plants every day for any unusual growth.
“With hemp and cannabis, you h ave to walk your fields or monitor your plants every single day to ensure that there are no hermaphrodites or pollen on the plants, as it will affect the rest of your grow,” states Perlowin. “It is surprising how fast something can go wrong so it is important to watch closely. If you don’t find these plants, you could be jeopardizing not only your crops, but also those of other growers .”
Finally, swiftly remove any male flowers that appear. If the plant has very few male flowers, those flowers can be removed, but the plant will need to be watched closely. Plants with many male flowers should be eliminated entirely.
“We found that it is better to remove the entire plant than cutting off the problematic branches,” explains Perlowin. “We do this by using a large plastic bag to cover the entire plant. Without shaking the plant, we move the bag down to the very bottom of the plant, seal it, cut the plant down at dirt level, then take it off the property.”
How can you tell a male plant from a female plant?
To a non-expert grower, all cannabis seeds look alike. The gender of cannabis plants becomes more readily apparent when the plant approaches the flowering period .
Author Robert Connell Clarke’s book Marijuana Botany An Advanced Study: The Propagation and Breeding of Distinctive Cannabis presents clear instructions for differentiating male and female plants. The gender of a cannabis plant is located at the nodes along the main stem.
Male plants can be identified most easily when they begin flowering. The flowers initially appear as a curved claw shape, which soon differentiates into a flower bud containing five radial segments. As the flowers develop, pollen sacs emerge that almost look similar to small bunches of grapes. Eventually, the sepals of the pollen sacs will open to release the pollen.
“When you see a pollen sac, you will know that a female plant is turning male,” says Perlowin. “Oftentimes, you can tell before the pollen sack becomes a problem. You should examine the plant from the very bottom of the plant to the top. It is easy to spot when the pollen sacs are at the top of the plant, but be sure to examine if there are pollen sacs at the bottom.” Male plants additionally grow taller than female plants as they mature and have thicker stems and fewer leaves.
Female plants are generally shorter, denser in foliage, and broader than their male counterparts. Photo by: Gina Coleman/Weedmaps
Female plants usually take several days longer than males to develop pistils or female sexual organs. The pistils look like small green seed pods and have white v-shaped stigmas, or thin hairs, which extend from them. Female plants are generally shorter, denser in foliage, and broader than their male counterparts.
Can you turn a male plant female?
The sex of a plant is determined by its genetics before germination even begins. With the sex genetically encoded, there is no way to make a male plant female, or a female plant male. There are techniques that can be used, however, to encourage a male plant to display female characteristics. These techniques require the use of chemicals, such as ethylene , to prompt a hormonal response from the plant.
Elevated levels of female hormones in male cannabis plants can trigger female flowering development. The technique is more effective when applied to male plants that have not yet formed mature flowers. It’s also vital to bear in mind that many male marijuana plants are hermaphroditic plants, and distinguishing true males can be very difficult.
Can you clone a female from a male?
A true female cannabis plant cannot be cloned from a male plant. Cloning is a process that is used by breeders to make genetic copies of robust, healthy female plants, reducing the guesswork that sometimes accompanies cannabis cultivated from seed.
For growers who wish to grow female cannabis plants from seed, the availability of feminized seeds can significantly streamline the growing process. Feminized seeds occur as a result of inducing a female plant to herm, then fertilizing another female plant with the pollen. The pollen from the ‘hermie’ contains only female chromosomes, so that no true males can result from the seed.
Male vs. Female Cannabis- Why it’s important to know before you grow
Just like humans, cannabis and hemp plants are considered dioecious, meaning they have either male or female reproductive organs. Depending on the goal of the cultivator, it’s crucial to know the gender of their plants prior to harvest.
Both male and female cannabis plants have their benefits; growing both can result in cross-pollination and thus seeds, resulting in new genetics or seeds for the next crop. However, if your goal is to produce quality buds rich in cannabinoids, it’s crucial to isolate the males from the females to avoid pollination and seed production. Cannabis pollen is extremely potent; studies have shown that pollen can drift across 3 to 7.5 miles, and can reach over 30 miles if high winds are present.
Removing males will allow the female plants to grow abundant, seedless buds (called sensimilla ). When female plants are left unfertilized, they use that extra energy meant for reproduction to produce higher levels of cannabinoids like THC or CBD, depending on the strain. The resinous buds consumers purchase at dispensaries are all sensimilla.
How to Visually Determine the Sex of a Cannabis Plant
Cultivators can visually determine the gender of their plants about 4-6 weeks into the growth cycle (though this may differ for indoor grows) when the plant is transitioning from its “vegetative” stage into the “flowering” stage. At this time, the plant is no longer focusing its energy on growing bigger and taller and instead spends all its effort growing flowers for pollination and reproduction.
When a cannabis plant is beginning to enter the flowering stage, cultivators should pay careful attention to the area between the nodes of the plant, where the leaves and branches extend from the stalk. Pre-flowers will begin to form in the nodes of the plant, and characteristics of the pre-flower will vary based on gender.
Pre-flowers can initially be difficult to examine with the naked eye, but growers can use a magnifying glass to get a closer look. Female cannabis pre-flowers grow as tiny bracts which will eventually produce hair-like stigma; male plants produce small, round balls as the nodes.
In some cases, a plant may exhibit both male and female pre-flowers. Hermaphrodite cannabis plants can occur when a plant becomes excessively stressed due to things like plant damage, bad weather, disease, nutrient deficiencies, and poor genetics. Hermaphrodites can also produce anthers, often referred to as “bananas” due to their appearance. It’s important to monitor plants that have been exposed to stressors to ensure they don’t begin to develop both male and female genetics. Hermaphrodites are capable of producing pollen and can ruin an entire crop.
How to Determine Gender Before the Pre-Flower stage
Lab genetic testing can determine a plant’s gender as soon as it begins to sprout its second set of true leaves. Knowing sooner can help cultivators save money, increase canopy space, and decrease labor costs associated with transplanting, watering, monitoring, training, and removing unwanted male plants.
Just as humans have X and Y chromosomes, cannabis also has a genetics system that determines the plant’s gender. However, figuring out the gender based on the DNA of a plant prior to the flowering stage is not as simple as looking for an X and Y. Luckily, the specific genetic sequence that differs between female and male plants has long been discovered, so using quantitative polymerase chain reactions (qPCR) allows labs to determine the gender of any plants with 100% confidence.
When a sample is brought in to Infinite Chemical Analysis Labs for gender identification, qPCR analysis is used to determine if the plant is female or male. A small hole is cut out of the leaf of the plant and added to a lysis solution to destroy the plant cell walls, exposing the DNA. After isolation of the DNA, it is transferred to another plate that contains reagents to amplify and cause the sample to create a fluorescent light that our qPCR instrument then quantifies, and determines the gender of the sample based on the amount of fluorescence.
Between sufficient lighting, proper nutrients, a detailed watering schedule, and constant monitoring, identifying the sex of your plants is another tedious yet crucial task that could make all the difference come harvest season.
Gender identification testing is now available at InfiniteCAL to help cannabis and hemp cultivators take the guesswork out of their grow. If you’re interested in learning more about Gender Identification Testing, reach out to our team at [email protected] .
Understanding Male, Female, And Hermaphrodite Cannabis
When you grow cannabis plants, they will either turn out as females, males, or hermaphrodites, meaning a hybrid of the two sexes. Knowing the difference between the three is vital to maintaining a strong growing operation, whether you’re planning on crossbreeding strains, maximising the yield of your female plants, or studying each of the types.
Cannabinoids, terpenes, phytochemicals, organic cultivation
Cannabis Breeding – Genetics – Tissue Culture – Quality Control
A guide to differentiating between male, female, and hermaphrodite cannabis plants.
- Why does it matter that cannabis is dioecious?
- Male vs female cannabis: what’s the difference?
- Hermaphrodites: when cannabis plants become monoecious
- Can you tell if your plant is male or female before flowering?
- How to identify different sexes of cannabis plants: sexing cannabis
- Types of hermaphrodite cannabis plants
- How to avoid hermaphrodite plants in your grow room
- How long does pollen last in a grow room?
- What type of cannabis seeds are used for breeding?
- Can you tell the sex of a cannabis seed?
From psychoactive cannabinoids to aromatic terpenes, cannabis features many traits that make it unique within the plant kingdom. However, the uniqueness of the plant doesn’t stop at the phytochemicals it produces.
See, the vast majority of plant species are monoecious, a term meaning they possess both male and female reproductive organs in the same plant. These include edible plants, such as corn and squashes, that can readily fertilise their own flowers using their own pollen.
Cannabis belongs to a minority of species that are dioecious in nature, meaning they produce separate male and female plants. Specifically, it should be noted that only 5-6% of all angiosperms (flowering plant species) possess this rare and interesting trait.
Why Does It Matter That Cannabis Is Dioecious?
Cannabis growers and breeders use this trait to their advantage, since it allows them to separate male and female plants. This enables growers to prevent the flowers from becoming fertilised and going to seed, which results in better-quality flowers, known as sinsemilla.
It also means cannabis breeders have more control when it comes to crossing specific males and females together. They can choose two healthy and vigorous specimens, place them close together, and produce progeny that express certain traits.
Let’s take a deeper look into male and female cannabis plants. From there, we’ll see what causes some specimens to develop both male and female reproductive organs.
Male vs Female Cannabis: What’s The Difference?
Male and female plants look identical during the seedling and vegetative phases. But, as they begin to transition into the flowering phase, plants finally begin to reveal their sex. During this time, females produce resinous buds loaded with cannabinoids, and males form sacs filled with pollen.
Female cannabis plants are the main focus of casual growers looking to harvest a personal stash. But, depending on their genetics, female plants can look drastically different from one another. Some remain small, producing dense canopies and significant lateral growth. Others grow in excess of 3m, produce massive harvests, and look more like trees than regular garden plants.
Despite their differences, all female plants share one thing in common: they produce female flowers. These flowers, colloquially known as buds, possess small glandular structures called trichomes that produce cannabinoids such as THC and CBD.
Male plants, in contrast, don’t produce female flowers. This makes them less valuable for growers seeking only buds. However, they do produce pollen sacs. These small vessels create the genetic material required to fertilise female flowers and produce seeds. This makes the males extremely important for breeding new cannabis strains.
It should also be noted that male pollen sacs and female flowers develop at the same point on the plant. Both structures emerge from nodes, the point at which branches meet the main stem. So, when you see buds starting to form on some plants, start looking for pollen sacs too.
Hermaphrodites: When Cannabis Plants Become Monoecious
Cannabis, like those who love it, doesn’t always stick to the rules, though. Sometimes, this dioecious plant species goes against the grain and develops both male and female reproductive organs. These specimens are known as hermaphrodites. Either genetic or environmental factors, or both, can cause plants to develop this unusual trait. Having both buds and pollen sacs, they end up developing the ability to pollinate and reproduce with themselves.
Of course, growers want to avoid this phenomenon if they’re aiming for the best flowers possible. We’ll dive deeper into what causes hermaphroditism and how to avoid it below.
Can You Tell if Your Plant Is Male or Female Before Flowering?
Yes, thankfully. While males pose a threat to growers chasing nothing but resinous buds, you can prevent them from entering your grow room altogether if you know what to look for. You don’t have to wait for pollen sacs to develop—and risk them spilling their genetic material—in order to spot the males in your crop.
Before entering the flowering stage, cannabis plants begin to reveal their sex in the form of preflowers—the early developmental stage of buds and pollen sacs that form around the nodes (the point at which the branches and main stem meet). However, it takes some time—up to six weeks—for preflowers to display obvious male and female features.
How Soon Can You Tell if Your Plant Is Male or Female?
Luckily, male preflowers show key characteristics earlier than their female counterparts. This enables attentive cultivators to remove male plants from the growing space well before female plants start to bloom. Typically, males reveal their sex two weeks earlier than female plants. You can expect to see preflowers begin to appear by the sixth week of the growing cycle.
How To Identify Different Sexes Of Cannabis Plants: Sexing Cannabis
The ability to determine plant sex as early as possible is a critical skill for cannabis growers. Know as “Sexing Cannabis”, as you develop this eye for identifying plant sex, you will be able to prevent any accidental pollination.
The goal: find the males and move them out of your grow room or garden as quickly as possible. The sex of a plant becomes fairly obvious during the early flowering stage, but time is of the essence in that regard. The quicker you can identify and remove male plants, the more you reduce the chances of accidental fertilisation.
Identifying Early Signs Of Male Plant
Growers identify plant sex by identifying pre-flowers, which are small structures that form at the nodes during late vegetation.
During the early flowering stage, take a stroll around your grow room or garden with a magnifying glass or jeweller’s loupe. Inspect a few nodes on each plant to see how far along into the flowering process they are. At this stage, you won’t see any obvious flowers or pollen sacs. Instead, you’re looking for young pre-flowers. Although these tiny structures look similar, they have distinct features that allow growers to tell them apart.
Male pre-flowers look like tiny green eggs or “balls”. These young pollen sacs will look smooth and won’t possess any fine hairs, or any distinct point. Later into the flowering stage, pollen sacs begin to form larger and denser clusters. They’ll become easy to identify with the naked eye by this point. However, pollen sacs usually begin to disperse their contents around 2–3 weeks after forming. Be sure to remove them from your space with haste if you don’t plan on crossing your plants.
The difference between male and female flowers becomes more obvious as they grow, but cultivators with a keen eye can tell them apart at the earlier stages. Male preflowers, anatomical landmarks known as staminates, are much more spherical. They feature a round sac accompanied by a long piece of protruding tissue. Together, these structures are referred to as the “ball and stick”. If left to develop, male preflowers will quickly transform into hanging sacs loaded with pollen. Other characteristics of male plants also help to give their sex away. These morphological differences include increased height, thicker stems, and fewer leaves.
Identifying Female Cannabis Plants
Female pre-flowers also develop at the nodes. You can distinguish them based on one obvious visual characteristic: hairs. Female pre-flowers feature tear-drop shaped calyxes with small hairs protruding from the tip. These small hairs, known as pistils, are the sex organs of female cannabis flowers.
These protruding structures are designed to capture pollen, which leads to fertilisation. They stick out away from the flower to capture pollen from the air, and to await being brushed up against by pollen-covered insects.
Within a matter of weeks, these small pre-flowers swell into dense nuggets and begin churning out cannabinoid and terpene-rich resin. Since you the removed males and prevented pollination, your flowers will continuously produce resin until the end of the growing cycle.
Identifying Hermaphrodite Cannabis Plants
Several factors can cause female plants to start to develop pollen sacs—or exposed stamens—alongside their flowers. This trait means that plants don’t need to rely on a nearby male to burst their sacs and fertilise them. As we’ll discuss in a bit, this is actually a savvy survival mechanism and a display of nature’s genius. However, hermaphrodites aren’t desirable in the grow room or garden. Now, let’s discuss both types and how to avoid the issues they cause.
Types Of Hermaphrodite Cannabis Plants
Hermaphrodite cannabis plants come in two different forms: true hermaphrodites and “bananas”.
The former features distinctly male and female reproductive flowers. Upon close inspection, you’ll notice male flowers occupying some nodes, and female flowers residing at others. When the pollen sacs rupture, the pollen will displace into the pistils, and the plant will effectively breed with itself. From there, it’ll produce seeds that will give rise to the subsequent generation.
“Banana” hermaphrodites get their name from their physical characteristics. Instead of producing separate male flowers, they only develop a bare stamen without sepals within the female flower. This naked appendage drops pollen directly onto buds to ensure self-reproduction. These stamens share a similar shape and colour to a certain tropical fruit, hence their name.
How To Avoid Hermaphrodite Plants In Your Grow Room
Hermaphroditism stems from two major driving factors: stress and genetics. In regards to stress, hermaphroditism serves as a survival mechanism. If a plant experiences damage, heat, disease, or nutrient deficiencies, they start to freak out. Essentially, plants get the impression that their time is up. In a last-ditch attempt to reproduce, they decide to stop waiting around for a male and get the job done themselves.
To avoid this issue, try to maintain a stable environment in your grow room. Use a thermo-hygrometer to monitor temperature and humidity, keep your light schedule strict, and ensure your plants get all the nutrients they require.
Even if you have all of these bases covered, plants can still pollinate themselves due to genetics. Plants with a bad genetic history can inherit genes associated with the expression of male flowers, producing hermaphrodites.
How Long Does Pollen Last in a Grow Room?
Under the right conditions, breeders can store pollen over a period of years for breeding purposes. However, this fertilising substance doesn’t last as long when exposed to the volatile environments of grow rooms and gardens. Pollen grains lose their viability upon exposure to water, heat, and light; these elements are commonplace within any growing environment.
Once a male plant opens its pollen sacs and spreads its genetic material, it only remains viable for a matter of days. If disaster strikes, the female plants in the vicinity will almost certainly divert their energy away from resin production and toward seed formation. While your current plants won’t turn out exactly the way you had hoped, this doesn’t mean you need to sterilise your entire grow room and all of your cultivation gear.
The pollen in the environment will lose its viability to less than 5% within approximately three days  . Considering you’re more careful with identifying sex going forward, you don’t have to worry about residual pollen contaminating your next wave of female plants.
What Type Of Cannabis Seeds Are Used For Breeding?
If you want to try breeding, you’re going to need regular cannabis seeds, and Royal Queen Seeds offers a premium range. In contrast to feminized seeds that produce only female specimens, regular seeds offer a 50% chance of the plant being male or female.
These seeds provide breeders with an army of males and females to experiment with. Cross the very best specimens together to create your own unique strains that match your taste. However, if you’re growing for nothing but buds, you can still use them for their stable and trusty genetics. As you may know, regular seeds provide excellent mother plants to produce clones and amazing yields. You’ll have to spot male plants, but the payoff will be more than worth it.
Can You Tell the Sex of a Cannabis Seed?
No. Believe us, we’d be thrilled if this was the case! No matter what your local ganja guru might tell you, growers simply can’t identify the sex of a plant based on staring at the seeds. Seeds aren’t plants. Without key anatomical areas to assess, such as preflowers, leaves, and stems, seeds provide absolutely zero clues about their future sex.
However, seeds do give away some indications regarding their quality. Their colour, sheen, size, shape, and even source serve as great means to predict their vitality. Unfortunately, these signs do nothing to point toward their fate as either a male or female plant.
The only way to know the sex of the seeds is by checking the DNA in the laboratory. For this, it would be necessary to extract the DNA from the embryo and apply molecular markers that detect regions of the male chromosome. Nonetheless, this method will destroy the seed and is highly expensive, so it is better to wait for the appearance of the preflowers to determine the sex.