Leaf Symptoms:
Abnormal Growth
Other Symptoms:
Buds Not Fattening
Remove plants with both male pollen sacs and female flowers (hermies) to avoid pollination/seeds!
You may also see yellow "bananas" (stamens) growing on the buds. A stamen normally grows inside a male pollen sac but sometimes they 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 on the buds!
This is a hermie male pre-flower that also has two female pistils sticking out. Immediately toss plants that show both male and female flowers!
Male vs Female Cannabis Plants: Introduction
Cannabis Life Stages and Gender
Did you know there are “male” and “female” cannabis plants? Yes, cannabis plants are “dioecious” plants, which means each plant shows a particular gender, just like humans and many animals. There will occasionally be plants that show mixed gender 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 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. There is no way to know for sure if a particular male plant is going to produce THC/trichomes, and 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 seed banks, 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. More information on how to ensure you grow only female plants is located in the Grower Toolbox below the main article. It’s impossible to look at a young cannabis plant and know its gender.
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.
There is no way to inspect a vegetative cannabis plant (like the following) and know the gender
Unfortunately, there currently is no way to determine for sure what gender a plant will be when it’s just a young seedling, and throughout most of the vegetative stage. In fact, scientists still don’t fully understand exactly how gender is determined among gendered plants like cannabis. So far, no one has pinpointed a “male” chromosome or any other known factor that causes a plant to develop into a male or female.
However, we do know that cuttings (clones) taken from a female plant will always turn out to be female. We also know that when you breed two female plants together, you end up with feminized (all-female) seeds. While we know that these methods are effective for growers, the exact mechanism of why and how this happens is not yet fully understood.
So unless you start with a known female clone or feminized seeds, there’s no way to know what gender 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 gender?
Cannabis plants reveal their gender when they reach their second stage of life, known as the “Flowering Stage”.
The first sign of gender 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's not certain whether this plant is going to turn into a boy or a girl quite yet.
Sometimes, when a plant is 6 weeks or older, or if the plant is a clone, it will begin to show pre-flowers while still in the vegetative stage. This is normal and is just a sign that your plant is fully mature and ready to start flowering. On the other hand, some plants never show pre-flowers no matter how long you wait, so you don’t need to wait until your plant shows pre-flowers before you initiate flowering.
Younger plants (that are less than 6 weeks old) tend to take a few days 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 plant to flower no matter what the age, even immediately from seed.
Myth Alert! I recently received this question:
“I was told that you want a male plant [close enough to female plants] to make the hairs sticky. Is that what makes weed sticky?? I told her I didn't think you wanted the male around your female plants while flowering. She said she's done it that way for years. So now, I'm confused! I was pretty adamant about what I thought (that male plants should be thrown away so it doesn’t pollinate your female plants) but she was just as adamant. We agreed to disagree! But what the hell do I know? :) She said she had a divider between them.. I’m pretty sure I don't want a male plant near my crop, what’s your take on this?”
Answer: This is just a myth. Getting sticky buds has almost everything to do with your genetics and the growing environment. There is no known benefit to having a male plant around while preventing the male plant from pollinating your females.
When Gender 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 plant 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-gender 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 hermis.
Important: It's not advisable to breed mixed gender plants to create seeds because their offspring could be more likely to display hermie characteristics.
Hermaphrodite Plants
Although growers will refer to all plants with gender problems as “hermies,” there are technically two different kinds, hermaphrodite cannabis plants, and mixed gender buds like buds with nanners. The only reason I bother to differentiate between the two is because 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 examples of a true hermaphrodite plant - notice how this hermi 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 gender plant seems to be a little bit more based on the plant’s genetics. A clone of a true hermaphrodite plant will often also turn into a hermaphrodite, and offspring will often show the same traits. It does not take much stress for these plants to hermie.
It is recommended to not 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 and as long as the grower keeps close watch.
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 gender buds you will see plants that grow a mix of pistils and pollen sacs together, like this...
Bananas (“Nanners”)
Another very common type of mixed gender buds is with the production of “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, giving them the nickname “banana”. They also often 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 start pollinating everything in the area as soon as they appear. If you have a big banana problem, it may be best to harvest the plants immediately and cut your losses.
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 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.
The yellow bunches in this bud are bananas/stamens and will pollinate everything they can - they don't have to wait for a pollen sac to burst
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 does play a role in whether a plant is capable of producing bananas and mixed gender 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.
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).
Heat - When temps get too high hermies and nanner often appear.
Too-Bright Light - Like too much heat, 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 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 bananas to start growing.
Genetics - While stress plays a big role in the formation of bananas, the tendency to form them seems to be genetic. This tendency is very common in the seeds of a plant that hermied - these “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.
What should the grower do? It is recommended that you remove plants showing bananas from your grow room or 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 gender” cannabis plants, plants with mixed gender buds (especially hermies with bananas) are the least predictable and most likely to cause unwanted pollination. This is partially because with bananas the pollen sac doesn’t need 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.
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 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 flowering 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 what 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 to produce 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 filter 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 too much messing up the light schedule can cause hermies.
2.) Maintain Proper Temperature Through Flowering Stage
Maintain a comfortable temperature in flowering stage, between 65-85°F (18-30°C) - temps should be slightly cooler at night than during the day.
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!
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 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, 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
A huge stress to the plant can cause the plant to react in unpredictable ways, including producing bananas and male pollen sacs. Huge stresses include...
Major nutrient deficiency
Nutrient Burn - given too much nutrients
Pest infestation
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 being female.
5.) Always Start With Trusted Genetics
Hermaproditism and mixed gender buds seems to be more common when growing plants from bag seed (seeds that you find) or seeds from an unprofessional breeder.
Do feminized seeds cause hermies?
The reason this is so is because 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 negligence (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 gender traits.
Which cannabis breeders can I trust?
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!"
~Jorge Cervantes
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