As every grower knows, cannabis is a dioecious species, meaning it produces some plants that are exclusively female and others that are exclusively male. However, because mother nature loves to break her own rules, some cannabis plants actually contain both male and female sexy bits, and are the … “A single hermaphrodite can pollinate an entire grow room, rendering the cannabis flowers useless.” Learn more about hermaphrodites in the world of cannabis here. Do you know what hermaphroditism is? How to differentiate it from intersex? In this post we disclose those and other doubts…
What To Do With Hermaphrodite Cannabis Plants
As every grower knows, cannabis is a dioecious species, meaning it produces some plants that are exclusively female and others that are exclusively male. However, because mother nature loves to break her own rules, some cannabis plants actually contain both male and female sexy bits, and are therefore known as hermaphrodites. While this is fairly rare, most growers will come across hermaphroditism in their crop from time to time, so it’s important to know how to handle these plants.
As we explained in a previous post, it’s generally pretty easy to identify the sex of a cannabis plant, as females are adorned with pistillate flowers while males are hung with stamens that are often referred to as “bananas” because of their appearance.
Hermaphrodites are female plants that also contain one or more banana. These stamens can sometimes form inside the female flower itself, replacing the pistil, but will more often appear alongside the female inflorescences, occupying some of the plant’s nodes (where the branches meet the main stem).
A recent study found signs of hermaphroditism in five to ten percent of plants that were being grown indoors under commercial conditions[i]. While the frequency at which this occurs varies between strains, it’s clearly important to keep monitoring your plants throughout the flowering phase in order to spot any unwanted hermaphrodite inflorescences before they get a chance to self-pollinate.
The development of male stamens on a female flower, from emergence (a) to full maturity (f) over a period of three weeks. Image: Holmes et al. (2020)/Fronties in Plant Science
What’s the problem with hermaphroditism?
When growing cannabis it’s essential to prevent the females from being pollinated, which means your growing area needs to be a banana-free zone. This is because all of the cannabinoids are contained within the female flowers, which will grow to their maximum size if they don’t get fertilised. However, once pollinated, these plants will divert most of their energy to the production of seeds instead of resin, resulting in low-quality weed that is full of seeds but distinctly lacking in cannabinoids and terpenes.
To avoid any unwanted hanky-panky within the growing area, it’s become common practice to remove (and often destroy) the males, leaving the females to reach their full flowering potential. Yet this arrangement can be scuppered by an undetected hermaphrodite, which can easily fertilise an entire crop if it isn’t dealt with before its anthers open and release their pollen. So if you have meticulously eradicated all of your males but still end up with weed that is full of seeds, you know that one of your females must have developed into a hermaphrodite.
The production of pollen by a hermaphrodite inflorescence, from the development of anthers (a) to the release of pollen (d). Image: Holmes et al (2020)/Frontiers in Plant Science
How to prevent hermaphroditism?
While hermaphrodites may be a real nuisance, it’s worth remembering that all life on Earth has evolved with one purpose: to survive. In keeping with this universal drive to endure, cannabis hermaphroditism has developed as an adaptation to help the plant reproduce quickly when it feels threatened.
As such, it is always more likely to occur when the plant is under stress and thinks it needs to go to seed. This stress can be caused by any number of environmental factors, such as the overuse of pesticides and fertilisers, interruptions to the photoperiod, pruning during the flowering phase, too much or too little water, undesirable temperature or the presence of pests.
Eliminating this stress by providing the optimal growing conditions is therefore the best way to reduce the frequency of hermaphroditism in your crop. To do this, you’ll need to diligently monitor and control all of the above factors, while also making sure to harvest your flowers at the right time. If flowers become too mature without being fertilised then the plant may take matters into its own hands and start sprouting bananas so that it can self-pollinate. Knowing when to harvest can be an art in itself, and is typically determined by the colour of the trichomes, which turn from clear to milky to amber as they develop.
It’s also important to bear in mind that some strains will simply be more genetically prone to hermaphroditism than others, so it’s worth doing some research on this before buying seeds.
What to do with hermaphrodite plants
Given that the priority is to prevent pollination from occurring, you’ll always want to get rid of any male flowers. If a hermaphrodite plant has numerous bananas on it then it’s probably a good idea to just eliminate the whole plant, although in some cases it may be possible to just remove the male flowers using tweezers, if there are only one or two present. However, it’s important to be extremely careful when doing so, as the last thing you want is to accidentally spread some of the pollen.
Alternatively, if you notice male flowers starting to appear on female plants at the end of the flowering period then it could be a sign that its time to harvest, in which case you’ll want to start picking your bud without delay.
Of course, all of the above only applies if you are just trying to grow high-quality bud, and it’s a bit of a different story if you are actually attempting to breed plants. Obviously, male flowers are necessary for this purpose, so you won’t be eliminating these while breeding. It’s also here that hermaphrodite plants really come into their own, as the seeds produced from self-fertilised hermaphrodites always give rise to female offspring.
Commercial breeders therefore rely on hermaphrodites when creating feminised seeds, and often introduce chemicals like silver nitrate to deliberately stimulate the production of hermaphrodite inflorescences.
The rest of us, though, need to be on the lookout for any unwanted stamens on our plants, otherwise we could find our sinsemilla dreams are dashed by an undetected hermaphrodite.
Hermaphrodites: A word derived from the names of the Greek deities Hermes and Aphrodite; hermaphrodite is meant to convey the presence of both sets of reproductive organs. Cannabis, as some unfortunate growers may know, can develop this trait if stress occurs in sufficient quantities. A single hermaphrodite can pollinate an entire grow room, rendering the flowers useless. Light stress is the most common culprit, in which light leaks and broken timers can spell disaster! Check for any holes in your sealed grow room, and ensure timers are operating correctly to spare yourself this pain. However, hermaphrodites are the objective for some gardeners. Hermaphrodites are an essential aspect for the production of feminized seeds. In this case growers will spray a solution of colloidal silver on their plants during the first weeks of the flower cycle. The silver solution interrupts the production of female reproductive organs leaving a hermaphrodite. These plants are then left to self-pollinate and produce seeds that are 99.9% female, while maintaining the genetic traits of the parent.
Hermaphroditism in Cannabis plants. So, what now?
Among cannabis plants we can find dioecious and monoecious specimens, that is, individuals that only show a defined sex and others that contain flowers of both sexes in the same plant. Originally they were all monoecious, as is the case with almost all varieties of industrial hemp as well as the vast majority of vegetables on the planet.
In the past this was not a problem, because cannabis was used for making fibres and the seeds were eaten, so every plant was valid. Then they started smoking the flowers after removing the seeds, as well as producing hashish centuries later, and they soon realized that female plants were much better for these purposes, or that they barely showed any male flowers.
It was the human hand that began to isolate the best females for its own use, and by selection and crossing the dioecious traits were fixed in some pure varieties. From the best stable Landraces came the first hybrids, and from them most of the polyhybrids we know nowadays. The vast majority of cannabis seeds nowadays are of well-defined sex, but there are still genetics that can show hermaphroditism and this is what we will see here. What is a hermaphrodite cannabis plant and what can we do with it?
Meaning of Hermaphrodite
I guess we’ve all been there at one time or another, we have arrived to the crop and among all the plants we saw something strange. Something that you do not expect, a plant that has strange things in the buds and when you approach to see it well your predictions are confirmed, it is a hermaphrodite sex flower, but what is hermaphroditism?
The definition of hermaphrodite in marijuana plants means specimens containing both sexes in the same flower. This process is also called Monoceia. This can be a big problem if you want to smoke the buds, because male flowers normally pollinate female flowers and your buds will contain seeds. So, is hermaphroditism bad? It is for us, although we have to understand that sometimes it is a positive reaction that the plant shows on certain situations.
Picture showing the different sexes of cannabis plants*
⭐ Types and causes of Cannabis Hermaphroditism
- Environmental stress
- Culture Stress
- Chemical agents
- The most common cause of weed plants showing hermaphrodites is genetic. As we saw before, the ancestors of all the current varieties were hermaphrodites, but they have been working over the years to stabilize their sex. Many times plants contain hermaphrodite genes in a recessive way, that is, some specimens may not show it, but these same specimens may pass it on to the offspring. It is also the case of varieties that always show pure females when grown optimally, but can end up showing male flowers in stress situations.
- Environmental stress hermaphroditism is quite common too, but in this case it has to do with Darwin’s theory of evolution. It may seem like a negative thing, since it can ruin your crop, but it is actually a system of adaptation to the environment, since it happens when the female plant perceives that it can die due to environmental irregularities, so it produces male flowers to self-pollinate and procreate as soon as possible.
- Crop-induced stress can be caused naturally or by the grower himself/herself. Pure Afghani genetics have minimal water requirements, because they are used to dry and unfertile soil, and when you try to grow them in a rainy area they often show hermaphroditic signs. It also happens the other way around, of course, if you bring a Mexican to Afghanistan it’s normal for it to get stressed out too and it can end up hermaphroditing. This can be seen very well with some hybrids when they are over-fertilized, or when they suffer from water stress due to drought, excess irrigation or an inadequate PH in the nutrient solution.
- Hermaphroditism caused by over-ripening can be suffered by 90% of today’s commercial cannabis varieties. It is a kind of survival system of the plant, which when it perceives that its death is near and has not been fertilized, creates some male flowers to self-pollinate and try to continue with the lineage. There are many sexually stable females that endure many types of stress without showing any hermaphroditic signs, but in the case of over-ripening they end up producing hermaphrodite flowers.
- Cannabis has the ability to reverse or invert its sex thanks to certain chemicals. This is because there are some elements that have the capacity to inhibit the ethylene production of the female specimens, and therefore show male flowers capable of producing pollen. An example of this type of hermaphroditism is STS which is used to produce feminized seeds. Plants reversed with silver thiosulfate, colloidal silver or other chemicals, we call them hermaphrodites, although they are not really like that, because when they start to generate male flowers they stop producing female flowers, so maybe we could call them sequential hermaphrodites or just intersex plants.
Image of an intersex cannabis plant, where you can see a female flower next to a male one*
Difference between hermaphrodite and intersex
We usually call all plants containing both sexes hermaphrodite and it’s actually like this. But we must differentiate between those that produce both female and male flowers separated in different areas, which would be intersex ones, from those that form male and female flowers in the same bud.
➕ How to take advantage of a hermaphrodite plant?
The best thing you can do when you detect a hermaphrodite plant in your crop is to carefully remove it so as not to spread the pollen in case it has opened the flowers. But that doesn’t mean that you have to cut it down and throw it away, because sometimes you can get some use out of the plant.
Some specimens can take out 1 or 2 male flowers and nothing else, it happens sometimes with pre-flowers, in the fourth or fifth knot usually, that can be taken out and the plant will continue to flower as a female many times. It is convenient to keep an eye on these specimens if they are mixed with other females, in case at some point they take out some little banana (male flowers that come out in some hermaphrodite buds).
There are also some hermaphrodite plants that can take out a few small bananas in a bud, visible and that can be removed with tweezers. In these cases it is also better to separate them carefully and, depending on the development of the buds, choose whether to bring forward the harvest or keep them under supervision until they finish their cycle. Once you’ve removed the bananas, you can use that weed like any other.
If it is a plant that shows signs of continuous hermaphroditism during the first weeks of flowering, it is best to cut it directly if there is a danger of pollination of other females. If this happens to you, you should know that you can use the plant to make rubbing alcohol, for example. However, if you have to cut it with a more advanced flowering stage, I suggest you try to make BHO, because if the buds already have resin I feel that this is a better way to take advantage of a hermaphrodite.
And if they are seeds from a hermaphrodite plant, can I use them?
One of the factors that influence hermaphroditism is the genetic as we saw before, it is one more inherited characteristic that runs from generation to generation. Therefore, seeds that come out of hermaphrodite marijuana plants have a good chance of also being hermaphrodite.
Sometimes we find some seeds among the whole harvest of a plant, which usually come from self-pollination, they are the so-called S1. This happens when a little banana comes out and fertilizes a small area of a bud, so only a few seeds come out, sometimes only one. These seeds are feminized and very similar to the plant from which they come out, they always come out female, but they are always prone to produce some male flower between their buds as well.
How to avoid that a plant becomes hermaphrodite?
This is not always possible, because there are some varieties that have it very marked, intrinsic. But there are many others that only have a tendency to hermaphroditism, or a greater ability to produce flowers of the opposite sex. This tendency has a lot to do with the ability of genetics to withstand stress, those that are sexually pure, very few, endure much more stress without showing changes in their sex. If you want to stop them from showing it, consider the following factors:
- Don’t go crazy with nutrients
- Check the pH and regularly calibrate your meter
- Daytime temperature around 75º F. (24º C.) and at night around 64.5º F. (18º C.)
- Keep the crop clean, pests also stress
- Strict photoperiod and no illumination of the plants during the night period
- Don’t delay the harvest, you know that over-ripe ends in hermaphroditism
- Be careful with phytosanitary products, some are very strong and can stress the plant
- Don’t put too many plants in too little space, root stress is also bad
You’ve seen that hermaphroditism in cannabis is not a bad thing in itself, even if it bothers us. At least you know how to handle it and how you can take advantage of these plants in case this happens. I hope you liked this post, and if so, I’d like you to share it.