Much like humans and (most) animals, cannabis reproduction usually starts with a male and a female plant. This kind of biparental reproduction is called dioecious (coming from the Greek word διοικία, meaning “two households”). However, contrary to vertebrates, the sex of plants can not be predetermined.
Hermaphroditism can naturally occur in every life form on earth. Usually, regular marijuana seeds are equally male and female. However, things are not as clear-cut in cannabis as it is in other beings: the sex of marijuana is largely determined by its environment. This basically means that plant can change sex depending on the conditions they are growing in. Hermaphroditism in cannabis is a failsafe mechanism used for plant reproduction under extreme conditions.
Chances are that at some point you have come across seed banks selling “feminized” seeds. This is because female plants are the only ones able to produce flowers (or buds) filled with the psychoactive compounds that give cannabis all its medical and recreational traits.
Male plants are generally undesirable to people that do not care about plant propagation (although they are by no means useless). Seed banks have been trying to alleviate the situation via a complicated process called “feminization”. Put simply, this technique involves the deliberate change of a female plant’s sex to male. This forcefully changed plant produces pollen that increases the chances of the resulting seeds being female.
No matter how confusing this sounds, it goes a long way to show that the sex of cannabis is of utmost importance to the growers. To make matters worse, there is no telling what gender a plant is going to be until the early flowering stage. In the vegetative stage, all plants look the same. Not even science has managed to isolate a “male” chromosome that can help us identify a seed before it sprouts. The earliest you can identify your plant’s sex is during the pre-flowering period.
There are some ways to make sure that you end up with female plants:
- Taking clones out of a female;
- Breeding seeds from female plants (feminization);
- Buying feminized seeds (70-90% chance of a female plant.
Although most plants are growing to be either male or female, there are occurrences of hermaphroditism in either sex. These plants show both male and female traits and they can potentially ruin crops. Below we will find out what they are, how to spot them and how to avoid any unpleasant situations caused by them.
What is Hermaphroditism and How is it Caused
Hermaphroditism depends on both genetic and environmental factors. Usually, the hermaphrodite traits of a plant are imprinted on its DNA and they won’t show until something activates them. Some strains (like the Thai) have historically had a disposition for hermaphroditism. However, most cases of hermaphroditism in cannabis plants (hermies) occur due to environmental factors.
Hermaphrodite plants develop both male (pollen sacks) and female (pistils) characteristics. Genetics aside, this is a survival mechanism that is triggered when the plant realizes that the conditions for flowering and reproduction are less than ideal. In a desperate attempt to procreate, the plant will gain the traits of the opposite sex, in order to pollinate its own flowers.
Mixed-gender plants will either manifest themselves as hermies or “bananas”. This aptly named metaphor refers to what is scientifically known as stamen: yellowish, elongated pollen sacks growing from the center of a female plant.
Their size, shape and cluster-like growth resemble bananas, hence the name. The difference between regular pollen sacks and bananas is that the latter do not burst. Instead, they produce pollen and spread it to the buds that are near to them, making them harder to control.
There are quite a few things that can cause plants to change into hermies. Some of them are:
- Light leaks during the dark period of flowering;
- Extreme fluctuations in the pH levels;
- Over / underwatering;
- Exposition to high temperatures (above 80ºF/27ºC);
- Growing outside the recommended harvesting period;
Basically, any condition that can make your plant feel uncomfortable can trigger hermaphroditism, especially if there is a genetic predisposition. Choose your genetics carefully and be ever vigilant in the pre-flowering and flowering periods.
Spotting Hermaphrodite Plants
In the vast majority of cases, hermaphrodite plants are bad news for your crop, so that makes identifying them an important task. On the bright side, finding them is rather easy, since you can easily spot the male and female flowers coexisting.
Bananas are easily distinguishable by their characteristic color and shape. Remember that male pollen sacks will resemble little balls that are quite different than female pistils. However, you still need to watch out for smaller male flowers hiding under the leaves. It is common to discover male flowers growing on a bunch of female flowers. In such cases, pollination has already taken place and there is not much you can do about it.
Hermies in Early and Late Flowering
If you spot any hermies lying around, it is important to remain calm and not rush into hasty solutions (like cutting off all extraneous parts). If a plant shows hermie (or even male) traits during early flowering, remove it from your growing space to save your other female plants from pollination.
If you spot only a few male parts, you can always try to carefully remove them with a pair of sterilized tweezers. Remember to spray some water on them before proceeding, as this will neutralize the pollen.
In case hermaphroditism occurs in late flowering, harvest the plant as soon as possible.
Avoiding Hermaphrodite Plants
Avoiding hermies is as easy as proper care for your plants. Basically, you need to pay attention to some basic plant needs and you will be alright for the most part.
Be Wary of Light Leaks in the Flowering Period
When your plant is in its flowering phase, it needs a steady 12/12 light cycle. This means 12 hours of uninterrupted illumination, followed by 12 hours of absolute darkness.
In order to be able to provide absolute darkness for your plant, you need to make sure that your grow room is completely lightproof. This also includes lights entering through cracks, lights coming in from the street or even tiny indicators on electrical devices.
When your plant is flowering, it becomes sensitive to external stimuli. Photoperiods is how plants perceive the passage of time. Too much messing with it will cause hermies to show up, among a multitude of other problems.
Watch out for Leaf Symptoms and Deficiencies
This one is almost a no-brainer, but diseases and deficiencies might cause a plant to turn into a hermie. We have covered leaf symptoms extensively in the past but generally, in order to avoid hermaphrodites, you should regularly inspect your plants for:
Maintain a Proper Grow-Room Temperature
Unless you are growing with supplemental CO2 and HID lighting, the proper temperature for a grow room hovers around 65-80ºF (18-27ºC). Anything more than that is excessive and harmful to your plants.
The golden rule for temperature is that if the canopy feels too cold for the top of your hand, it’s too hot for your plant! Regulate your grow room temperature accordingly and buy a thermostat if needed!