Published: May 3rd, 2021
Categories: Cannabis Cultivation
When it comes to cannabis plants, seeds are probably the most important aspect of a growing operation. Regular seeds, which are roughly 50% male and 50% female, tend to be much cheaper than their feminized counterparts, so it’s only natural that a grower might ask the question: “Can you tell if cannabis seeds are male or female?”.
If this were indeed possible, it would save the average grower some money, not to mention time, when buying seeds. But, is it possible to sex cannabis seeds? Let’s find out.
This is the hot topic of the decade, if not the century! The modern cannabis grower is all about THC-loaded buds, or CBD ones, that are dripping with resin, cannabinoids, and terpenes. But, what does this have to do with the sex of the plant?
We need a short biology lesson. Cannabis plants are dioecious, which means female and male reproductive organs are found on separate specimens. The exception is the case of a cannabis plant becoming hermaphroditic, but this is often the result of stress and doesn’t occur regularly—we’ll explain more about this later in the article.
Because cannabis is dioecious, plants will either be male, with pollen sacs, or female, with pistils. The latter will bear seeds if pollinated, or will grow as sinsemilla (smokeable) buds if no pollination occurs.
Sinsemilla buds (Spanish for “without seeds”) is the desired product sought by cannabis users. This is because non-pollinated female plants don’t waste any energy on the production of seeds, but instead channel it towards bud growth and resin development, resulting in flowers with a higher amount of cannabinoids (THC, CBD, etc.), terpenes, and other cannabis chemicals.
This brings us to today’s question: can we determine the sex of cannabis plants by looking at seeds only? Let’s have a look at which factors influence the sex of cannabis plants, and urban legends surrounding this incredibly important aspect of cannabis seeds.
We already mentioned how cannabis is dioecious, so male and female traits are expressed in separate plants. But, which factors influence whether the seed will grow into a male or female plant? Fundamentally, the most influential factors are nature (the actual genetics of the seed) and nurture, which are the growing—and stress—conditions of the plants.
This is the most important determinant of cannabis plant sex. In optimal growing conditions, the sex of the plant is determined by the genetics in its DNA. The keyword is “optimal”. This is where nurture comes into play.
The main objective of male plants is to spread the pollen and fertilise as many flowers as possible to reproduce and continue the lineage. This is important to know for a couple of reasons: one single male plant can fertilise hundreds or more female plants, so you need to separate (and possibly eliminate) males as soon as you identify them if you wish to save your yields. If you are breeding, pollination is exactly what you are looking for.
This is also essential to know because stressed plants could potentially express hermaphroditism, where a single specimen shows both female and male traits. This can happen for several reasons. Environmental stress (light, temperature, over-fertilisation, wrong humidity level, etc.) can all negatively influence a plant, which, in response, feels threatened and is forced to produce pollen to fertilise itself and save the lineage.
Interestingly enough, this is one of the ways feminized seeds are created. When you stress a female plant, the pollen created won’t have any male DNA, and therefore the seeds resulting from the self-pollination won’t have any male DNA either—hence “feminized” seeds.
Short answer? No. Long answer? It’s virtually impossible to find out the sex of a seed by looking at it. The only way is to germinate them and wait until plants start showing pre-flowers, which will indicate the sex of the plant.
Despite the scientific certainty surrounding seed sexing, it doesn’t stop myths and urban legends from making their way around blogs, charts, and articles. Let’s see two of the most common ones.
Some say that the crater-like hole you can find on cannabis seeds can help you determine the sex. More specifically, they claim that a perfectly round crater equals a female seed. Well, as we mentioned earlier, the only way to determine sex is by growing the seed, so don’t waste your time analysing your seeds with a microscope searching for the roundest crater ever created!
Apparently, female seeds are believed to roll more easily across a surface than male seeds. Again, you can have some fun rolling around cannabis seeds on your table, but this won’t tell you anything regarding the sex of your future plant!
So, when can you determine the sex of your plants? The moment a plant starts to shift its energy from vegetating to developing flowers, also known as the pre-flowering stage, is the best time to look out for signs of sex.
The male plant will develop ball-like structures at the nodes, which will become fully formed pollen sacs as the plant develops. Female plants, on the other hand, will develop immature calyxes, which will look like little white hairs (pistils).
You could force the flowering stage by subjecting your plants to a 12/12 light cycle to try and spot the male plants earlier in your growing operation. Once you have found and removed them, you can go back to the normal lighting schedule and continue with vegetative growth. However, this technique is very stressful, so we don’t suggest doing it to the entire plant. Instead, you can cover one branch on the lower half of your plant with a black, breathable bag for 12 hours a day. This way, this branch will be the only one to show pre-flowers, while the rest of the plant can continue to veg, free of stress.
And that is how you find out the sex of your cannabis seeds! If you wish to avoid all of the above, we suggest looking for feminized seeds. These have a 99% chance of growing into beautiful, sinsemilla female plants.