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Hermies, Pollen Sacs & Bananas

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Remove plants with both male pollen sacs and female flowers (hermies) to avoid pollination/seeds!

You may also see yellow “bananas” (stamens) growing around the pistils/hairs of the buds. A stamen normally grows inside a male pollen sac but sometimes appear directly on female buds, especially in times of stress. A stamen produces pollen and doesn’t even need to open up before it starts making seeds! Remove plants immediately if they start growing bananas (also referred to as “nanners”) or your entire grow room may get pollinated. No one wants to be surprised by seedy buds after harvest.

This highly stressed plant (from heat and too much light) grew a banana in a last desperate attempt to make seeds

Certain cannabis plants will herm even if healthy and unstressed. This is a genetic trait carried by some strains and particular plants. That’s part of why it’s important to grow seeds from a trustworthy breeder. For example, every clone of the following plant grew bananas in week 3 of the flowering stage, under no stress, in multiple different grow setups. When herming is part of a plant’s genes, there’s not much you can do.

These bananas weren’t triggered by stress. Herming is simply part of this plant’s genetics. The brown hairs are already pollinated.

Here’s a closeup of a herm banana

This poor hermie has male pollen sacs growing among the female flowers. It’s recommended to immediately toss any plant that shows both male and female flowers!

Male vs Female Cannabis Plants: Introduction

Cannabis Life Stages and Sex

Did you know there are “male” and “female” cannabis plants? Cannabis plants are “dioecious” plants, which means each plant shows a particular sex, just like humans and many animals. There will occasionally be plants that show mixed-sex and these plants are often referred to as hermaphrodites or “hermies”, which I will explain in much greater detail below.

The sex of a particular plant matters quite a bit to growers. That’s because only female cannabis plants produce buds. In fact, the “buds” that we smoke are actually the female flowers of the cannabis plant.

The highest quality bud is considered to be “sensimilla” and refers to female cannabis buds that have not been pollinated by a male cannabis plant. The word “sensimilla” actually comes from the Spanish phrase “sin semilla” which roughly translates to “without seeds.”

Regular marijuana seeds will usually be about 50% male, and 50% female. That means half of the seeds will be unusable as far as growing buds. Please note that some male cannabis plants (about 70% of male cannabis plants according to some estimates) may produce a small amount of useable THC via trichomes growing on the outside of the plant. Unless you’ve seen the males in your plant’s family tree, there is no way to know for sure if a particular male plant is going to produce THC/trichomes. Even if it does it will be a much, much lower amount than a female cannabis plant producing buds.

If you have a male plant and you are trying to grow bud, I strongly, strongly recommend throwing the male plant away immediately and starting another seed or focusing on your other plants. It’s a waste of time to grow male plants for THC or other cannabinoids – they don’t grow buds!

Here’s a picture of a male cannabis plant – no buds or trichomes, just pollen sacs!

Quick Tip: How do you make sure you only grow female plants so all your plants produce buds?

One way around the issue of having 50% male and 50% female plants is to purchase feminized seeds online. These seeds are available from all reputable online seedbanks, and the plants produced by these seeds are always female. Get your questions about buying seeds online answered! You can also make your own feminized seeds, but you have to start with two known female cannabis plants.


It’s difficult to look at a young cannabis plant and know its sex

For the first part of your cannabis plant’s life, it will be in the first stage of growth known as the “Vegetative Stage.” In this stage, your plant will only grow leaves and stems, but no buds or flowers. Think of this as the time when your plant is gaining size to prepare for the second stage of life.

A young vegetative cannabis plant is unlikely to reveal its sex until it’s at least 3-6 weeks old, and sometimes even later than that.

Unfortunately, it’s difficult to determine the sex of a cannabis plant when it’s a young seedling. Although there is genetic testing that can be used on plants as young as 1 week old, most growers aren’t going to go that route. At a certain point, most strains will “reveal” their sex via pre-flowers at the joints. This can occur as young as 3 weeks old with male plants, and around 4-6 weeks old for female plants. This is normal and is just a sign that your plant is fully mature and ready to start flowering. Learn more about preflowers.

Another great option is to use clones. Cuttings (clones) taken from a female plant will always turn out to be female. Sometimes clones are showing preflowers by the time they’re rooted as a clone. We also know that when you breed two female plants together, you end up with feminized (all-female) seeds.

So, unless you start with a known female clone or feminized seeds, there’s no way to know what sex your plant will turn out until it actually starts showing signs of sex organs. This happens in the second stage of your plant’s life, known as the “flowering stage.” The first sex organs that appear are often called “pre-flowers.”


When do cannabis plants reveal their sex?

In addition to looking for preflowers, all cannabis plants reveal their sex when they reach their second stage of life, known as the “Flowering Stage”.

The first sign of sex almost always appears at the “V” where new growth tips form from a stem, like this….

See the little growths appearing at the “V” or “crotch” where the growth node meets the stem? These are the first sign of “pre-flowers“. In this case, we can see the pre-flowers are forming, but it could be tough to tell whether this plant is going to turn into a boy or a girl quite yet. (Note: It’s a boy)

Younger plants (that are less than 6 weeks old or haven’t shown preflowers yet) tend to take a little longer to switch into the flowering stage compared to older, more mature plants that have been vegetating for a while. Other than that, you can pretty much force a cannabis plant to start flowering no matter the age, even 2-3 weeks after the seed was germinated.

Read the full article about male vs female cannabis plants (and learn how to use cloning to identify the sex of young plants while they’re still in the vegetative stage – advanced only!): https://www.growweedeasy.com/marijuana-boy-girl

When Sex Isn’t as Certain… Avoid Accidental Pollination!

So now you know that most cannabis plants are normally considered to be either “male” and “female.” Yet sometimes you will run into plants that show both male and female characteristics, and these plants can accidentally self-pollinate, or pollinate your other female plants.

A cannabis plant that shows both male and female parts is often referred to by growers as a hermaphrodite or “hermie.” These can pollinate your plants and cause seedy buds.

There are a few different types of mixed-sex plants, and it’s important for a grower to understand some of the biggest differences so they make the best decision possible when faced with hermies.

Important: It’s not advisable to breed mixed-sex plants to create seeds because their offspring are more likely to display hermie characteristics.

Hermaphrodite Plants

Although growers will refer to all mixed-sex plants as “hermies,” there are technically two different kinds: hermaphrodite cannabis plants, and mixed-sex buds (like buds with nanners). The only reason I bother to differentiate between the two is that true hermaphrodite plants are more predictable.

With a “true” hermaphrodite plant, the male and female parts will grow on different parts of the plant. They won’t grow together in the same spot such as when nanners appear in the middle of buds.

Here is an example of a true hermaphrodite plant – notice how this hermie has both female pistils and fully formed male pollen sacs

What causes it? Stress can trigger this type of hermaphroditism, but unlike bananas, this particular type of mixed-sex plant seems to be a little bit more stable based on the plant’s genetics. It usually doesn’t take stress to cause these to appear. They’re more like a natural trait of the strain. A clone of a true hermaphrodite plant will often also turn into a hermaphrodite, and offspring will often show the same traits even under perfect environmental conditions.

It is recommended to never breed a plant that shows hermaphrodite traits since this is a highly inheritable genetic trait. A good “breeding stock” mother will not show signs of hermaphroditism even when subjected to stress.

What should the grower do? It is recommended that you remove hermaphrodite plants from your grow room or grow area as soon as possible to prevent accidental pollination of the buds.

If pollen from a pollen sac is allowed to make contact with your buds, those buds will stop focusing on making more buds and will turn all their “effort” into making seeds. No one wants seedy buds and reduced yields!

Unlike bananas, hermaphrodite plants tend to be more predictable. Though it’s not advisable, a grower who watches very closely can carefully pluck all pollen sacs before they’ve burst. However, this should only be done if it’s the only plant you have! Don’t do this if you have other female plants that can be pollinated!

Remember, while these pollen sacs can start appearing early, they may continue to appear throughout the flowering stage so stay vigilant!

The following type of hermaphrodite plant has mixed male and female parts, referred to in botany as “bisexual” flowers.

With mixed-sex buds you will see plants that grow a mix of pistils and pollen sacs together, like this…

Bananas (“Nanners”)

Another common type of mixed-sex buds is the type that produces “bananas” (sometimes called “nanners”) which grow from the middle of female buds.

Example of a “Banana” or “Nanner” growing among buds

Bananas are rarely round and they don’t look like a normal pollen sac. Instead, they’re often elongated and yellow, which is where they get the nickname “banana”. They may grow together in bunches that can look like a bunch of bananas. Occasionally they appear more lime green than yellow.

Sometimes a banana appears lime green instead of yellow

These can be a lot more difficult to control than actual pollen sacs, since they may start pollinating everything in the area as soon as they appear. A few bananas won’t do much damage, but if you have a big banana problem it may be best to harvest the plants immediately and cut your losses. Seeds take some time to develop, so if a plant starts herming right around harvest time, it’s less likely you’ll end up with seeds.

Just like real bananas, they can appear in bunches

What are they? Bananas are actually the exposed “male” parts of a pollen sac, called the “stamen” which would normally be surrounded by a sac to hold all the pollen until it bursts open. If you open up a fully formed male pollen sac, you will see what looks like bananas (stamens) inside.

But when bananas appear on your plants, they don’t need to “burst” in order to spread pollen, they will immediately start making pollen and often will seed the buds that are close by even if bananas are removed right away, and sometimes the pollen can drift to other plants and pollinate them as well, too.

This banana appeared a few days after the grower used the bud back building technique (cutting off the top tip of all buds to try to get them to grow more fat and round). Apparently, the plant felt attacked

This is what it looked like after being picked off

It’s possible that the pollen is sterile, and won’t pollinate bud successfully…but don’t rely on that happening!

The yellow bunches in this bud are bananas/stamens and will “try” to pollinate everything they can – they don’t have to wait for a pollen sac to burst. It’s possible that the pollen is sterile, but often you may find seeds.

If a female plant is allowed to go too long without being harvested or pollinated (allowed to go past the point of optimal harvest), she will sometime produce a bunch of bananas in her buds as a last-ditch attempt to self-pollinate and create seeds for the next year. This is sometimes known as rhodelization. This is not as destructive as other types of hermies since it only happens after plants are already past the point of optimal harvest.

What causes it? While genetics are ultimate the cause of whether a plant is capable of producing bananas and mixed-sex buds, environmental stress is often a big component in causing bananas to form. Luckily if you stick with high-quality genetics, you are much less likely to run into bananas even if you do accidentally stress your plants. Not all bananas are “fertile” and you may see them without ever getting seeds.

Male hermie banana growing among the beautiful buds 🙁


What type of stress can trigger bananas to form on cannabis buds?

Inconsistent Light Schedules & Light Leaks – When plants don’t get light at the same time each day, or if they’re exposed to light during their dark period (light leak). For photoperiod plants, this might be the largest contributor to hermies.

Temperature – When temps get too high, hermies and nanners often appear. Cold night temps, or just large temperature swings in general, are also known to trigger bananas for some strains.

Too-Bright Light – Like too much heat, and/or light that is too bright can stress your plants and trigger hermies. This is most often caused by growers keeping their lights to close to their plants. You can light-burn your plants even when the temperature is under control.

Major Plant Problems – Major plant problems like nutrient deficiencies, root rot, pH problems, light-burn and nutrient burn can all trigger hermies to start growing.

Genetics – While stress plays a big role in the formation of bananas, the tendency to form them is genetic. This tendency is very common in the seeds of a plant that hermied. “Feminized” seeds, while always female, are much more likely to show the same herming traits as its parent. Growing seeds that were produced this way is naturally selecting to produce more buds that grow bananas. Only get feminized seeds from a trusted breeder.

What should the grower do? It is recommended that you remove plants showing bananas from your grow area immediately to prevent accidental pollination of buds. If the pollen being formed is allowed to make contact with your buds, those buds will stop focusing on making more buds and will turn all their “effort” into making seeds. If the plant self-pollinates, you will end up with a bunch of sub-par seeds that are likely to have the same problem.

Of the different types of “uncertain sex” cannabis plants, plants with mixed-sex buds (especially hermies with bananas) are the least predictable and this can make them more likely to cause unwanted pollination. This is partially because bananas may be hidden in the buds, and they don’t have a pollen sac that needs to burst to pollinate buds – it will start pollinating almost immediately.

A grower who watches very closely can carefully pluck all bananas, but they are unlikely to be successful and will probably end up with at least a few seeds.

Trying to salvage a plant that has started producing tons of bananas is NOT recommended, because it’s hard to get them all and you’ll end up with seeds. Even worse, once a plant gets started, bananas can appear in huge bunches overnight especially when the plant is stressed. Harvest the plant as soon as you can, before seeds get a chance to start forming.

How to Avoid Causing Hermies or Bananas

This section will explain what you can do as a grower to reduce your chances of running into hermies or bananas in your grow room…


1.) Avoid Inconsistent Flowering Light Periods & Light Leaks

Keep indoor lights on timer, and avoid changing the light schedule during the flowering stage if possible.

Prevent outdoor plants from being exposed to street lights, flood lights or other types of artificial lights during the night.

Respect the dark period – In the flowering stage it’s important to make sure all your plants (except auto-flowering strains) get at least 12 hours of uninterrupted darkness every night. Avoid shortened dark periods and light leaks!

No matter the strain, try to keep your plants on a consistent schedule throughout their lives, as this helps them set their circadian rhythms.

And for photoperiod plants in the flowering stage, do not interrupt the plant’s 12-hour dark period with light for any reason.

Why? During the dark period your plant is “counting” the hours until sunlight appears, and interrupting this process is one of the most common ways to stress the plant into producing bananas or hermies. It can also cause your plant to revert back to the vegetative stage.

Along with the point above, make sure you do not have any light leaks in your grow space, which could allow outside light to sneak in during the dark period. During the dark period your plants like complete darkness.

If anything ever happens with your timer or power that causes your plant to get too much light or darkness, it’s important to correct your timer as soon as possible. But don’t worry about it too much if it happens just for one day. It’s usually okay if it happens only once, but be careful not to let it happen again since messing up the light schedule can cause hermies. It’s better for a plant to get a too-long day than a too-short night period in the flowering stage. So, for example, it’s better for it to get an 18-hour day than a 6-hour night. Cannabis plants “count” the hours of the night period, so it’s most important to make sure the night period is at least 12-hours long (longer is better than shorter for night periods).


2.) Maintain Proper Temperature Through Flowering Stage

Maintain a comfortable temperature in the flowering stage, between 65-85°F (18-30°C).

Avoid big temperature swings – temps should be slightly cooler at night than during the day.

  • Don’t let the plant (and their roots) sit directly on a cold floor.
  • Always use “hand-test” to make sure it doesn’t feel too hot in the top canopy of buds under the light. Put one of your hands (palm facing down) under your grow lights where the top of your plants are located and wait 10 seconds – if it feels too hot for your hand it’s too hot for the plants! Be careful of cold drafts at night in cool climates during the winter.


    3.) Don’t Give Your Plants Too Much Light (Light-Burn)

    While generally more light is better for your cannabis plants, very high power brightness can light-burn your plants, which stresses plants, causes unwanted bleaching, and can trigger the plant to hermie on you.

    With high power LED grow lights and big HID lights, make sure to always follow the manufacturer’s specifications as far as the minimum distance from the top of the plants!

    Don’t keep your lights too close because even if the heat is under control, too much brightness can cause stress too.

    Light-burn is only common with high power LEDs (3W chipsets and bigger, x-lens technology, COBs, etc.) and big HIDs or perhaps multiple smaller HIDs (usually with an intense cooling system).

    It is more difficult to “light-burn” your plants with fluorescent lights, CFLs, smaller HIDs, etc. – with these lights, you only need to worry about heat.

    High Power LEDs or HID Grow Lights Will Light-Burn Plants When Kept Too Close
    (yes, even if the temperature is completely under control)


    4.) Prevent Major Plant Problems

    Major stress to the plant can cause the plant to react in unpredictable ways, including producing bananas and male pollen sacs. Major stresses include…

    Nutrient Burn – given too much nutrients

    Total leaf loss (usually as the result of overzealous defoliation or bugs)

    Any other huge stress to the plant

    Want to read about a real example?

    The plant pictured to the right was subjected to cold temperatures and then grew directly into the grow light, putting it under a lot of stress.

    From the grower Saberabre: “So I left this girl (or what I thought was a girl, notice the pistils at the bottom calyx) over the weekend and came back to the plant up in the light getting burned. Yikes! I’m not too sure what happened here but it got pretty cold the last few days. I think it’s a hermie…”

    A few days before this pic, the plant was just showing a few white pistils and appeared to be female.

    After the stress that it went through, the grower came back to a plant that was completely covered in male pollen sacs, with the first few white pistils being the only sign of this plant is female.


    5.) Always Start with Trusted Genetics

    Hermaphroditism and mixed-sex buds seem to be more common when growing plants from bagseed (seeds that you find) or seeds from an unprofessional breeder.

    The reason is that seedy buds are worth less than sinsemilla (unseeded buds). Therefore, if you find a seed in your bud, it likely was the result of either bad growing practices (male plants weren’t removed in time) or due to some type of problem (plants were stressed and self-pollinated, which means the next generation is most likely to do so).

    When you’re buying seeds from a trusted breeder, they go to great lengths to prevent unintended pollination, and they specifically select for plants that don’t ever show mixed-sex traits.

    And remember… even if you do everything right, sometimes you will run into hermie plants – it’s just a fact of growing. Sometimes these things just happen, for example…

    “I’ve always felt like seeded weed was not nearly as potent as sinsemilla and I do everything in my power to kill all males! Cannabis is so sneaky, though – last summer we had such wild weather that even a couple of clones turned out some male sex parts.”

    Experienced outdoor grower

    “Cannabis has both male and female plants. When both female and male flowers are in bloom, pollen from the male flower lands on the female flower, thereby fertilizing it. The male dies after producing and shedding all his pollen. Seeds form and grow within the female flowers. As the seeds are maturing, the female plant slowly dies. The mature seeds then fall to the ground and germinate naturally or are collected for planting the next spring.

    “Unpollinated, female cannabis flowers continue to swell and produce more resin while waiting for male pollen to successfully complete their life cycle. After weeks of heavy flower and cannabinoid-laden resin production, THC production peaks out in the unfertilized, frustrated sinsemilla!”

    Plant Symptoms

    • Bronze or brown patches
    • Brown or slimy roots
    • Brown or yellow leaf tips/edges
    • Buds dying
    • Buds look odd
    • Bugs are visible
    • Curling or clawing leaves
    • Dark leaves
    • Drooping plant
    • Holes in leaves
    • Mold or powder
    • Pink or purple on leaves
    • Red stems
    • Shiny or smooth leaves
    • Spots or markings
    • Twisted growth
    • Webbing
    • Wilting leaves
    • Yellow between leaf veins
    • Yellow leaves

    This page is part of our Plant Doctor series. You can use our tool to filter by symptom and help diagnose your plant.

    Learn the difference between male and female cannabis plants, and find out what to do with "hermies" (female plants showing male pollen sacs or bananas).

    How to Prevent, Detect & Manage Hermaphrodite (Hermie) Marijuana Plants

    Marijuana plants usually come in male or female versions. But sometimes a female plant shows primitive or even fully developed male floral structures that can pollinate female buds on the same plant and other plants. These sexually confused plants are called hermaphroditic (or hermie).

    You’re very wise to pay close attention to your buds as they mature to see if hermie floral clusters show up, because seeded hermie buds suck.

    The good news is that although some hermaphroditism is genetic and almost impossible to avoid, hermaphroditism is also caused by avoidable plant stress. So in some cases, if you fix your growing procedures and environment, you can eliminate the hermie flowers and avoid having pollen in your grow op.

    It helps to know exactly what you’re looking for. So take a close look at the main photo for this article of a plant 21 days into bloom phase.

    The top half of the photo shows the white pistils and other structures normal for an unpollinated 100% female flower.

    The bottom half shows male floral clusters that have already broken open and dispensed pollen that seeded female flowers on the hermie plant and buds of other plants.

    It’s very important to note this photo shows one of two configurations of a hermaphroditic plant’s floral structure. This type of hermaphroditism consists of fully-developed female and male floral structures on the same plant. In this type of hermaphroditism, the male floral structures look the same as if you had a 100% male plant.

    The male and female floral structures are usually separated from each other (as shown in the photo). There’s normal female bud above; below it (sometimes separated by a stalk node or at least 1/8th inch or more distance), you see fully-developed male flowers.

    The second type of hermie floral structure is more sinister and harder to detect because solo or small bunches of male pollen sacs develop amidst female floral structures.

    These structures can be very difficult to see because they might not be as tall as the female bud’s white pistil hairs. Sometimes they’re embedded deep inside a thick female bud so you can’t even see them from the surface.

    The following photo shows this second type of hermie structure. Growers call those little lime-yellow things “hermie nanners.” It’s a slang term for hermaphroditic structures that look like tiny yellow or light green bananas, hence the word “nanners.”

    The nanners are usually no more than 1/16 th to ¼ inch long, and can appear singly or in clusters. Clusters of nanners look like a miniature stalk of bananas on a banana tree.

    Take a look amongst the white pistil hairs slightly to the left of top-center in this bud photo, and elsewhere, and you’ll see the dastardly nanners!

    Nanners (officially called “stamens”) don’t often develop into full-size pollen-dispensing structures like flowers on 100% male marijuana plants, but still dispense enough pollen to seed buds.

    An important difference between fully-developed hermaphroditism and nanner hermaphroditism is that a primarily female plant with a significant number of fully-developed male flowers is most often caused by inherent genetics, not just plant stress. Indeed, hermie genetics strains often develop male and female flowers on the same plant even in the best grow room conditions.

    In contrast, nanners are mostly caused by plant stress and other unfavorable conditions. Genetics plays a role, but a much smaller role.

    “Many growers have had their hearts broken growing strains that might be otherwise desirable, but have the tendency to go hermie,” explains “Paul the Pro Breeder,” who founded and runs legendary North American seed breeding consortium New420Guy Seeds.

    “I make sure every strain we sell has been rigorously tested to ensure it doesn’t have inherent hermie traits, and is totally resistant to stress-triggered hermie issues,” Paul explains. “Sadly, some other seed companies don’t have that rigorous process. They sell growers seeds that carry covert flaws such as hermaphroditism, so growers end up with seeded buds instead of happy harvest. Fortunately, that doesn’t happen with our seeds.”

    When a grower is confronted with the type of hermie plant shown in the main article photo, the grower can be pretty sure the plant’s genetics are fatally defective. It would be worthless to grow those genetics again, or to breed with them.

    In contrast, plants with nanners may revert to 100% female’ floral structures when plant stress is eliminated, especially during early bloom phase.

    The bottom line is: when you have a multi-strain grow room, with all plants experiencing the same conditions, and only one strain develops hermie traits in two or more ideal growing seasons, assume that the strain has hermie genetic tendencies and is to be avoided at all costs.

    WHAT CAUSES HERMAPHRODITE MARIJUANA?

    Several things cause hermaphroditic cannabis flowers:

    • Genetics: Some cannabis strains, especially pure or dominant Sativa, naturally develop hermie flowers. Hermaphroditism is often a female marijuana plant’s attempt to supply pollen to itself when none is coming from male plants. Genetic hermie traits are also caused by breeders attempting to make feminized and/or autoflowering seeds, and by other breeding and seed creation mistakes.
    • If you leave marijuana plants in bloom phase “too long,” they often start creating hermie clusters. If you have robust resin glands and are in last two weeks of bloom phase when hermie features show up, test a bud to see how potent it is, and consider harvesting those plants before seeds have time to develop. It takes more than 2-3 weeks for seeds to mature, so if you see a few hermie features just before harvest time, you can let those plants grow until harvest in a quarantined grow tent, ensuring their pollen won’t pollinate other plants that have a longer time left before harvest.
    • Excessive High-Intensity Light: Especially when you’re using LED grow lights, it’s easy to overdose plants with light radiation without visibly burning their leaves. Using a professional light meter intended for LED grow lights, you’re looking for PPFD readings of about 500-700 during bloom phase in a grow room without added C02. More light than that may stress plants, which can lead to hermie flowers. Note also that hermie flowering can be triggered when grow lights are too close to plants, creating excess bud heat. Using a digital directional thermometer, monitor your leaf surface temperature and keep it under 87°F. Preferably, leaf surface temperature should be 76-86°F, depending on whether you’re adding C02 to the grow room or not.
    • Irregular light cycles or light leaks: You want your bloom phase photoperiod indoor marijuana plants in a timer-driven grow op that starts and ends the 12-hour bloom phase lights-on cycle at exactly the same time every day. You want zero light leaks. Even tiny amounts of light, such as the faint glow from an active power strip or the infrared glow on a security camera, can interrupt bloom phase dark cycle and create hermaphroditism and other problems. Light cycle problems aren’t seen in autoflowering plants, which flower on their own and have no need for a specified dark period.
    • Root zone stress: Overwatering, underwatering, incorrect nutrients and/or root zone pH, overfertilizing, underfeeding, inferior root zone substrate management, root zone pathogens and other problems create stress that can lead to hermie flowers.
    • Environmental stress: If grow room temperatures, relative humidity, vapor pressure deficit and other environmental conditions are harsh for your plants, stress from that can cause hermie flowers. If your marijuana plants are under attack from pests, gray mold, powdery mildew or other attackers, the resultant stress can trigger hermaphroditic flowers.
    • Unsafe cultivation practices: Stressing plants by pruning too much or severely pruning after bloom phase has started are examples of cultivation practices that can cause hermie flowers.

    Detect and Prevent Hermie Marijuana From Happening to You!

    Now let’s take a look at how to prevent and detect and hermie marijuana plants:

    • Use Only Quality Seeds & Clones: Use only high quality marijuana seeds and clones from reputable breeders such as this one. Before buying specific strains in seed or clone, query the breeder about hermie traits. Research the seller/breeder/strain to see if there are any online reports of hermaphroditism. Be aware that landrace strains, pure Sativa strains, and feminized photoperiod strains tend to develop hermaphroditism way more than hybrid strains, non-feminized strains, and mostly Indica/Kush genetics. Autoflowering cannabis rarely if ever develops hermaphroditism.
    • Strains that breeders specify as meant for outdoor cultivation sometimes develop hermaphroditism when you grow them indoors, and vice versa.
    • Ensure that your grow op cultivation procedures (watering, feeding, lighting, climate control, C02, air movement) and environment are ideal. Subjecting your plants to too much light, heat, C02, or nutrients is an example of how you create stress that can cause flowers to go hermie.
    • Avoid pruning after the first week of bloom phase.
    • Block pests and diseases from your grow room. They create stress that can trigger hermaphroditism.
    • Make sure your bloom phase light cycle timing is 100% consistent, with no deviation from grow light start and stop times, and no lights leaks or other interruption of the lights-off period.
    • Closely examine your plants beginning at the start of bloom phase, using the photos and the video in this article as guides so you immediately detect hermaphroditism as soon as it occurs. Use a magnifying glass or jeweler’s glasses (which have magnification built into the lenses). Not only are you looking for male floral clusters and nanners, you’re looking for pistils that used to be snow white but are suddenly turning brown or red–a sign that pollen has fertilized those buds. Unless you have male marijuana plants nearby, there’s only one place the pollen came from: hermie flowers.

    Managing Hermie Marijuana Plants

    What to do if you see nanners or male floral clusters on your female marijuana plants? Your tactics vary depending on your grow room set-up, when in bloom phase you detect the hermie structures, and what crop outcomes you can tolerate. Here are some case studies that offer strategy tips:

    Case Study A: The grower had a normal bloom phase until the last two weeks of an expected 9-week duration, when he first saw nanners in a few female buds. He saw no brown pistils or seed development. Knowing he’d be harvesting soon, he did nothing. He harvested the buds and when grading them discovered no seeds had formed.

    Case Study B: The grower saw nanners early in bloom phase on two plants from the same strain in a mixed-strain grow room. He made sure his grow room environment and plant inputs were optimized, spent a half hour per day inspecting plants for signs of pollination, and used tweezers to pluck off all nanners and the tiny parts of buds that showed pollinated pistils.

    After initial removal of all nanners, one plant never developed nanners again. He successfully harvested large, potent, unseeded buds from this plant.

    But the other plant continued to develop new nanners. The grower put it outdoors and let it grow until it was ready to harvest. The buds were partially seeded, but resinous and tasty. He used those buds to make extracts.

    Case Study C: A grower was cultivating pure Sativa genetics. The strain breeder had warned the grower about possible hermaphroditism starting in the middle of bloom phase. At 10 weeks into an expected 13-14 week bloom phase, male flowers developed.

    The grower isolated the hermie plant in a grow tent, and plucked the male flowers off on a daily basis. He lightly sprayed the affected stalks with water, because water is known to disable pollen, not just wash it away.

    He harvested about a week earlier than he’d have preferred, and found the buds to be potent, tasty…but about 35% seeded. The unfortunate thing is that other plants in the grow room were also partially seeded by the hermie pollen.

    Case Study D: A grower was manually controlling his bloom phase lights on and off, rather than using an automatic timer, and doing a poor job of it. His light control timing was so inconsistent—his poor cannabis plants were stressed by varying lengths of light and dark per day.

    They developed nanners in week three of bloom phase.

    We advised the grower to put his lights on a timer and ensure a strict 12 hour on/12 hour off formula, with the same start and stop time each day. He removed the nanners for seven days as the plants got used to the predictable light cycle. Then, his plants stopped producing nanners and were 100% female until harvest.

    His harvested buds were only 3-5% seeded. In subsequent grow ops, the same strain was grown; without light cycle stress, no nanners were observed.

    As you can see, marijuana growers are willing to work hard to detect and stop hermie structures from seeding their buds. They’d rather not have to get rid of a bloom phase plant if they can avoid it.

    However, to be 100% sure you won’t end up with a seeded grow op, the safest strategy is to get rid of hermie plants immediately, and make damn sure that non-hermie plants in the same proximity haven’t been seeded.

    Please watch the following fantastic video to get more understanding of hermaphrodite marijuana!

    Stop your marijuana plants from becoming hermaphrodite (hermie), and what to do if you can't!