Sexing Cannabis Plants in the Vegetative Stage: 4 Ways To Do It

Unless you are a breeder, you don’t want male plants in your grow room. Male plants are a nuisance to deal with. Their biggest downside is that they can end up pollinating your entire crop, but at the same time, they can be a pit for your resources, money, time, and energy.

Imagine tending to a plant for months only to have it turn out to be a male plant during the flowering stage. You don’t want that. This is why you must determine the gender of your cannabis plants as early as possible. 

Most growers sex their cannabis plants during the pre-flowering stage, which is pretty easy if you wait a bit. However, we will discuss a few ways to identify the sex of your cannabis plant during the vegetative stage itself. It takes more than a magnifying glass and some patience, but it is worth it. 

In this article, learn about the importance of sexing your cannabis plant, things to look out for, and how to find male plants in the process. 

Why Do You Need to Determine the Sex of Your Cannabis Plant?

There are a few reasons for sexing your cannabis plant, but for most growers — especially if you are reading this — the only reason is to weed out, pun intended, the male plants from your cannabis garden. This is crucial; miss this and you’re compromising your cannabis crop entirely. 

How does it really matter? Well, if you grow multiple plants and even one of them turns out to be a male — unnoticed — it will soon start developing pollen and end up pollinating all the other female plants in the grow room.

Once the female plants produce buds, they start developing seeds and are no longer high-quality buds. The very reason most growers put in all that effort and grow at home is to get pure sinsemilla buds without seeds. But, a male plant can put a dent in your plans. Your crop is essentially ruined because smoking seedy buds is never fun. The buds don’t offer the same experience anymore. 

Also, this shift in energy towards seed development reduces the plant's capacity for producing cannabinoids and terpenes, ultimately lowering the potency and quality of the harvested buds. Since growers look to enhance terpene levels in their buds, they prioritize removing plants to prevent seed formation.

Another reason why you want to avoid growing male plants is so you don’t end up wasting your resources and time on a plant that eventually does not give you any yield — a male plant will never grow buds. So, all the months of your hard work will go to waste. Removing plants in the vegetative stage allows you to optimize your cultivation space and resources for female plants that produce the buds you love. 

For breeders, this is especially crucial as it's critical to maintain purity. Male plants carrying undesirable traits can contaminate the gene pool if they pollinate plants. However, by removing plants early, breeders can safeguard the desired genetic traits and prevent any contamination of their breeding lines.

Even commercial growers take great care to avoid pollination and protect the quality and market value of their plants. Once female plants are fertilized and start producing seeds, their cannabinoid and terpene profiles may change, resulting in buds full of seeds, which isn’t appealing to consumers. In other words, they lose a lot of money. 

So, whether you’re a breeder, commercial grower, or home gardener, you need to protect your female plants and remove the male plants at a very early stage to prevent pollination. 

What Separates Male and Female Plants?

During the first two stages of the growth cycle, seedling and vegetative, both male and female plants are nearly identical. But when they switch to bloom, they start revealing their sex. When this happens, the male plants start developing pollen sacs that are filled with pollen. On the other hand, female plants start developing resinous buds. 

Remember, female plants can look drastically different from one another, depending on their strain and genetics. But there are some common elements that you can rely on. All female cannabis plants produce flowers.

The same rule applies to male plants, but instead of bushy flowers, they develop sacs that look like small peas. Pollen is nothing but a vessel of genetic material that will fertilize the flower. 

Unfortunately, both flowers and pollen sacs emerge at the same point on the plant, and at the beginning, it’s easy to confuse the two. So, if your plant starts developing flowers, it’s time to look closely to ensure they are not pollen sacs. 

Fortunately, there are many ways to tell the sex of your cannabis plants. Once you do that, you can eliminate the male plants from your grow room. But when can you do that?

As mentioned earlier, cannabis plants start showing their sex as they enter into the flowering stage in the form of preflowers — this is the early development stage for both pollen sacs and flowers. But it takes around six weeks for them to show distinguishing features. 

There are a few ways to surpass this and keep your female cannabis plants safe. 

Ways to Determine the Gender of a Cannabis Plant 

Many growers assume that it’s impossible to determine the sex of the plant during the vegetative stage. However, you can do so if you pay attention to some factors including visual cues. 

Cannabis, like many other plants, provides visual cues to help you understand how it grows. It’s possible to determine the gender even when the plant is young and in its vegetative phase. Although not always conclusive, experienced growers can differentiate between female and male cannabis plants by observing their physical traits. 

One of the indicators for distinguishing between male and female cannabis plants is the node arrangement. Female cannabis plants typically exhibit more calyxes at the nodes compared to males. Calyxes are structures shaped like teardrops found in the nodes. By examining the nodes on the branches and main stem, you can spot variations in calyx density offering clues about the plant's gender.

First off, differentiating between female cannabis plants requires a good grasp of their anatomy. You’ll notice that both females and males produce pre-flowers where stems or branches meet. Initially, the first signs of pre-flowers appear at the junction of the plant stem and a fan leaf stem, near the top of the plant. Interestingly male plants tend to show pre-flowers faster than females in anticipation of female readiness.

To spot pre-flowers look at the stalk/branch junctions. Consider using a jeweler's loupe for better visibility, similar to inspecting trichomes for harvest readiness. At this point, do not confuse the stipule, a small projection, as a pre-flower. Look behind the stipule and you’ll see the pre-flowers. Later, when the plant grows and advances into its flowering phase, you’ll see growth tips that will grow and produce buds. 

So, once the plants grow a bit, you can differentiate between the males and the females. But, how do you identify a male plant? With males, the pollen sacs that are often called pre-flowers will appear more rounder than female pre-flowers. They are also called spades as they resemble a spade in a pack of cards, due to the small tip and small round base. 

As the male plants grow, these sacs will look like a ball on a stick. Over time, the male flowers develop into elongated pollen sacs, but you shouldn’t wait until this stage to cull them. Although the pollen isn’t released yet, the risk is high because it can pollinate the females within just a few hours at times. 

If you’re very confused, hold off a bit and wait before culling the plants. You don’t want to throw away a perfectly beautiful female plant! Thus, look for other differences to make a good decision. 

For example, there are several variations between males and females even in the way they grow. While males exhibit a sparser growth pattern with fan leaves and wider gaps between branches, females will look slightly bushier and compact. That said, you cannot make a decision based on this factor alone. This is because it can get very difficult to notice these variations in some plants. 

Female plants tend to showcase a growth pattern with more lateral branches and denser foliage compared to males. On the other hand, male plants often appear taller and more slender with fewer branches and less foliage overall. By observing the structure and growth tendencies of the plants, growers can often deduce their gender based on these distinctions.

If you want to know the sex at an early stage and are ready to spend for it, you can use other methods to improve the accuracy. These methods include flowering tests and genetic analysis. Genetic analysis provides definitive information about a plant's sex based on its DNA profile. By combining these approaches, you can confidently determine the sex of cannabis plants. However, for a home grower, these steps are unnecessary. 

How to Spot Male Plants During the Vegetative Phase?

As mentioned earlier, spotting male plants isn’t obvious from the get-go since plants take some weeks to show distinguishing features between pollen sacs and flowers. But you can force the plants to show their reproductive organs through a few techniques. 

1. Clone the Plants

How does this work? Essentially, you clone a plant and make the clone preemptively bloom, skipping the entire growth process. 

Follow these steps.

• Take a Clone From Your Cannabis Plant

Start by taking a small clone cutting from your vegetative cannabis plants. You don’t need to pick the best branch or anything since you are not really cloning your cannabis plant. So, pick a branch with fewer nodes and one that isn’t likely to produce significant flowers. 

• Put It in a Glass of Water

Next, place the cutting in a glass of water. Again, you don’t need to apply any root hormone or go through any steps you would while cloning. Simply put it in water — regular light and water will still push the cutting to develop roots and grow a bit. Make sure the water does not evaporate. 

• Don’t Forget to Label Your Plants and Cuttings 

If you are growing multiple cannabis plants, you need to label each cutting and its corresponding mother plant. Otherwise, you may end up taking out a female plant instead of the male one. You don’t have to do anything high-fi here; a simple tape with the plant written on it will suffice. 

• Make Your Cutting Flower 

Once you’ve labeled your cuttings, take them into a separate space and put them under a 12/12 lighting cycle, which will initiate the flowering stage. The clones don’t need to establish a root network or grow big. After a few weeks, they will start revealing their sex. 

• Identifying Male vs Female Clones

This is where things get interesting. After up 1 to 3 weeks, they will start revealing their sex. As mentioned earlier, take a look at the joints where the stem meets the leaves. Here, female plants will develop white, wispy hairs and the male plants will develop tiny balls, like grapes.

Protip: use a magnifying glass to look at them. They can look a bit similar at first, but soon, the pollen sacs will start turning into balls. If you don’t take action at that point, the plant will produce bunches of them. 

• Remove the Male Plants

Chances are, you will spot a couple of male clones. It’s time to go hunting. Use the labels on your plant and remove their corresponding mother plants from the garden as they will also grow out to be male cannabis plants. 

With this process, you don’t have to wait for long and risk male plants pollinating female plants. Instead, you save time and resources — you don’t even have to grow a male plant only to eventually discard it. 

Then, you can continue growing your female cannabis plants as usual, and once they have reached the desired height, you can move them into the flowering stage. You will no longer have to worry about any rogue male plants ruining your crop.

2. Force Flowering

Another way to determine the gender involves forcing the flowering. This will also allow you to schedule your growing cycles precisely with faster harvests as you can shorten the time needed for plants to mature. You will also get continuous production if you’re into perpetual harvests.

The concept of force flowering simply involves manipulating the light the plants receive — something you do all the time when growing photoperiod cannabis plants if you want them to flower. As an indoor grower, you already know that cannabis plants need at least 18/6 hours of light during the vegetative phase and will start flowering once they get 12 hours of light and 12 hours of darkness. 

Once you alter the cycle, you’re letting the plants know that the season’s changing, thereby forcing them to start flowering. Due to the light manipulation, the plant experiences a hormonal change that triggers flowering. After a while, the plants will show pre-flowers that you’ll typically see near the nodes. This is the first step to identify whether the plant is male or female. 

To start with force flowering, wait at least 4-6 weeks after seed germination when the seedling has developed a few sets of leaves. Typically, you’ll wait until the plant spends a good amount of time in the vegetative stage. Once you’re okay with the size, you will then shift them to flowering. However, with forced flowering, you’ll have to shift them to flowering right away by changing the light cycle to 12/12 hours. 

If there are no light leaks and everything is fine, the plant will start showing some pre-flowers at its nodes. If you see small round balls instead of calyxes, you can remove them. If they are females, you can continue growing them as usual and harvest the buds after they are mature. 

One key advantage of force flowering — depending on how you look at it — is that you don’t have to exert yourself too much as you won’t have to train or prune the plants. You won’t have to do the tasks you do during the vegetative phase as the plant will have progressed to the flowering stage. For growers working with limited space or multiple plants, force flowering can help as it allows you to use it efficiently. 

Most importantly, if you live in areas where you have no option other than growing a plant that flowers very fast, force flowering will allow you to choose your favorite plant and still grow it without worrying about the weather. You will also reduce the likelihood of pests as the time it needs to grow is reduced significantly. 

However, it’s not all roses. There are quite a few disadvantages to force flowering. You’ve probably already guessed by now that the plants will not produce the yields you expect. Cannabis plants that spend a lot of time in the vegetative stage have more chances of giving you good yields as they develop strong branches, roots, and everything else necessary to perform well. Since you aren’t allowing the plant to work on its foundation first, it will not produce great yields. 

Also, making plants flower faster can stress them out if you don’t do it correctly. Sudden changes in light and environment might mess up how the plants grow naturally, leading to problems such as nutrient deficiencies and stunted growth. 

All that stress can even force the plants to develop both male and female organs or hermaphroditism. This can lead to self-pollination and seed production potentially affecting bud quality. In the end, it’s ironic that you might get exactly what you were trying to avoid in the first place. You force the plants to flower soon to determine the sex and avoid pollination, but forced flowering can make the plants produce seeds if you don’t do it properly. Therefore, experiment with some plants first to understand how they react, and then start with your favorite plants. 

3. Hormonal Induction

Hormonal induction is a method utilized by growers to speed up the development of pre-flowers so it's easy to determine the gender. This technique involves applying hormones or chemicals to activate the pathways that kickstart flowering. Although this method is effective, it may not be suitable for all growers due to its complexity and associated risks. 

Hormones play a crucial role in regulating physiological processes in plants, including flowering. The shift from growth to flowering is controlled by the interaction of multiple hormones such as auxins, gibberellins, cytokinins, and ethylene. By adjusting the levels of these hormones, you can trigger the flowering process in plants at any growth stage.

One hormone that’s commonly used is gibberellic acid — a substance that regulates plant growth by encouraging cell elongation and flowering in certain plants. Another hormone, ethylene, can also be applied to prompt flowering by activating genes associated with the flower development process.

Typically, these hormonal treatments can be administered to cannabis plants by spraying on leaves or drenching the roots with it. Be careful, though, as you need to follow the instructions provided by the manufacturer to ensure efficient outcomes. You must also take care of the timing as you can use them only during the vegetative phase to initiate flowering without causing harm to plant health.

Once you apply the hormones, plants typically begin developing pre-flowers within a short time. Or, there could be small pollen sacs. Now, you know what to do. Simply toss the males if you aren’t interested in collecting the pollen for breeding purposes. 

While using hormones to induce sex identification can be effective, you must be careful with the dosage. Beginners shouldn’t try this method as it requires a good understanding of the plant. Incorrect application or dosage of hormones can result in effects like stunted growth, malformed leaves, or hormonal imbalances. Also, remember that hormonal treatments may not be consistent on various strains. This is why you should experiment and observe the plant and then take action. 

4. Chemical Tests

Chemical leaf tests are another way to determine the gender of the plant. You can find out when the plant is still very young, usually within 1 to 3 weeks after sprouting. These tests involve using a piece of plant tissue, like a section from a leaf or a single cotyledon leaf to minimize any negative impacts on the seedling's development. 

You can also figure out the potency of the buds the plant will produce through these chemical tests. Although these tests are very accurate, it simply won’t make sense for a home grower as you can wait for the plant to reveal its reproductive organs to cull the males. But, for commercial growers, this testing could be a boon as it can not only determine the sex at an early stage and help save space (space is very important for commercial operations) but it can also detect the potency, thereby helping them grow super potent buds. 

Solution: Grow Feminized Seeds 

All of this takes too much effort and time, and if you agree, there’s an even better solution — try growing feminized seeds. 

Feminized seeds are genetically designed to only grow into female plants. Yes, there is a slight chance of one turning out to be male, but that is a very rare occurrence. 99.9% of the time, you won’t have to worry about anything. 

You can find feminized cannabis seeds at most reputable seed banks, and most strains these days have feminized counterparts, too. And if you are worried about them not being good enough, don’t worry. 

Feminized seeds are just as good as their regular photoperiod cannabis plants in every regard: flavor, aroma, potency, structure, visual appeal, height, growth, resistance to risk factors, and much more. 

One downside of feminized cannabis seeds is that they can be more expensive than regular cannabis plants, but considering the benefits they offer, the price is often worth your while. So, if you want to be sure about growing female cannabis plants and have a successful harvest at the end of the season, choose feminized seeds. 

Summary: Sexing Cannabis Plants in the Vegetative Stage: 4 Ways To Do It

Now that you know what it takes to determine the sex of your cannabis plants, it’s time to get started. Or not. Most growers aren’t in too much of a hurry. But, if you want to maximize the space you have, it’s important to find out the gender of the plant. 

Many growers purchase regular seeds as they cost less compared to feminized seeds. For such growers, these methods can really help. Imagine growing 10 plants only to find out during the flowering phase that 7 of them are males! Horrific, isn’t it? You’d have wasted a significant amount of time, resources, and money on the plants at that point. Also, these 7 plants won’t produce buds and are taking the space of 7 females that can give you juicy buds. 

If you don’t want to go through this, try out these methods to identify male plants and remove them before they can pollinate the females. 

Out of all the techniques mentioned above, cloning them is perhaps the easiest. Yes, you can force the plants to flower and detect the gender early, but you will be compromising on a lot of things including the yield. Thus, take the easy route and clone them. You will need a small space for the clones, though. The good news, however, is that you don’t need a big tent as you won’t be using them anyway. A small closet or even the balcony could work, as long as you have 12 hours of light and 12 hours of darkness. 

• Take clone cuttings of your vegetative plant
• Place the cutting in water and place it under a 12/12 light cycle to force flowering 
• After a couple of weeks, look for pollen sacs
• If you spot pollen sacs on any, discard the corresponding mother plant 
• And don’t forget to label your plants, please. 

That’s it. Follow these steps and you will never have to worry about accidentally growing a male plant in your grow room.