Can You Tell if a Cannabis Seed is Male or Female?
Friday August 17, 2018
W hen it comes to growing cannabis, sex is important. Not that kind of sex! We’re talking gender, as in being able to discern male from female. The reason for this is simple enough: only female seeds produce flower, also known as the buds you might have in your stash as we speak.
When it comes to growing cannabis, seeds can be male, female or hermaphrodites. Females produce the resin-secreting flower, and males make small sacs of pollen near the base of the leaves. Over the years, cultivators have learned that un-pollinated females (remember, males produce pollen) continue to make resin and flowers that have not been pollinated are much more likely to produce high-potency cannabis. But is there a way to know if a seed is female before growing?
Interested in growing? Click here to purchase your own seeds and start growing today!
Determining if a Seed is Male or Female
If what you’ve got is a handful of seeds, it’s pretty much impossible to tell which ones are male or female. The only way true way to tell the plant’s gender is to plant some seeds, then wait. After a period of several weeks, it will begin to pre-flower, or form a small bud in the crux of a branch. One of the first signs your cannabis plant is female is the appearance of pistillates that are wispy and generally white in color.
If you’re looking for more precise, science-based methods to tell your plant’s gender, there are several labs that can sex your plant right after germination – eliminating the lengthy (usually around 6 weeks) wait to learn its gender. Portland, Oregon start-up Phylos Bioscience is in the business of studying cannabis genetics, and they sell a “plant sex kit” that’s pretty simple to do, even for the not scientifically-inclined. Simply press a cotyledon, or embryonic leaf, onto the kit’s filter paper and send it to their lab. They then test the leaf for the “Y” chromosome to determine its gender, just as would happen for a human male.
What are Feminized Seeds?
While it’s basically not possible to determine the sex of a seed from a random bag of seeds, a practice known as feminizing is becoming quite popular. Feminized seeds are selectively bred to produce female plants, however, some growers do worry about some feminized seeds turning into hermaphrodites.
Despite the potential for hermies, if growing cannabis is more hobby than full-time endeavor, and you want to guarantee you’ll have some consumable product, knowing your seeds are female from the beginning is probably your best bet.
There are many companies that sell feminized seeds, but, buyer beware, do your research to make sure the seller is reputable, especially if purchasing online. Thanks to modern technology, most feminized seeds from reliable brands will be 100% female as advertised – but that doesn’t mean there aren’t people selling low-quality seeds out there.
Methods for Feminizing Cannabis Plants
If you have some experience growing cannabis and would like to bend a crop to your will to ensure that the seeds will be female, there are a few feminizing methods you might try. One such technique is to literally stress out a healthy female plant by interrupting the light cycle during flowering, called Rodelization Feminizing.
In the colloidal silver feminizing method, distilled water is mixed with pure silver and sprayed on female plants. This method works best when the plants are flowering. This results in pollen sacs being formed, which will allow the seeds to produce female plants.
Feminizing via the silver thiosulfate technique involves carefully selecting a nearly mature female plant, then spraying it with 50/50 mix of sodium thiosulfate and silver nitrate. This triggers a gender change, from female to male. Place this plant back with the others to pollinate other female plants, and female seeds are created.
How Important is Your Plant’s Sex?
How much time you want to spend figuring out the sex of your cannabis plants really depends on how much time and energy you’d like to devote to growing your own marijuana. If you are a medical cannabis patient or caregiver, for example, and need to know what kind of cannabis you are getting every time, buying feminized seeds from a trusted seller is the way to go. But, if you have some time, consider yourself a green thumb, and want to experiment with your grow, you could simply plant your seeds and see what comes up. Happy growing!
What are your thoughts on feminized seeds? If you’ve used them before, how did it go? Share your experiences in the comments below!
Erin Hiatt is a New York City-based writer who has been covering the cannabis industry for more than six years. Her work – which has appeared in Hemp Connoisseur Magazine, PotGuide, Civilized, Vice, Freedom Leaf, MERRY JANE, Alternet, and CannaInvestor – covers a broad range of topics, including cannabis policy and law, CBD, hemp law and applications, science and technology, beauty, and psychedelics.
If you're interested in growing cannabis, determining the sex of your plant is a critical aspect in the cultivation process. Learn whether or not you can tell if a marijuana seed is male or female and more information about feminized seeds.
Male vs Female Cannabis Plants
Table of Contents
Marijuana Life Stages & Gender: Only Female Cannabis Plants Make Buds
Did you know there are both male and female marijuana plants? Yes, marijuana plants show gender, and the sex matters a lot to the grower.
That’s because only female plants produce buds. How do you grow female plants?
Regular marijuana seeds will be 50% male, and 50% female. That means half of the seeds will be unusable as far as growing buds.
One way around this is to purchased feminized seeds online. These seeds are available from all reputable online seedbanks, and the plants produced by these seeds are always female.
You can also make your own feminized seeds, but you have to start with two known female plants.
When do marijuana plants reveal their gender?
Cannabis plants go through two stages of life, the “vegetative” stage and the “flowering stage.”
They first go through the vegetative life stage, which you can sort of consider its “childhood” since the plant is only focusing on growing bigger and taller, and gender doesn’t matter. At the beginning of this stage you usually can’t tell what the plant’s gender is.
However, once the plant is about 6 weeks old, it will usually show signs of “pre-flowers” which will alert you to the gender before the beginning of the flowering stage.
Pre-Flowers usually reveal the gender around week 6 from seed
Otherwise you must wait for the flowering stage
Next, cannabis plants switch to the flowering stage which means they stop growing bigger and taller, and instead spend all their effort growing flowers (the buds we want are flowers!). The flowering stage is like the “adult” stage of a cannabis plant since at this point it’s only interested in adult stuff like growing their male and female parts, then pollinating 🙂 In the flowering stage, plants start growing buds or pollen sacs in earnest. The buds we want are female flowers, so growers generally only want to grow female plants.
Growers Want Female Cannabis Plants – These Produce Bud
Regular Marijuana plants reveal their gender in two situations:
After spending a long time in the vegetative stage – some strains/plants will show preflowers (pistils for girls and “balls” for boys) during the vegetative stage if they grow old enough, even when they are constantly kept under a vegetative light schedule. For example, clones can come from plants that are several years old, so you’ll see a lot of clones have female pistils showing, yet will not continue to flower any more than that until after they’ve been switched to a Flowering (12-12) light schedule
Otherwise, all remaining plants will reveal their gender in the first 1-3 weeks after lights are switched to 12-12, and plants enter the flowering stage of life.
Diagram Showing What Pre-Flowers Look Like
Male pre-flowers on left – Female pre-flowers on right
Female Marijuana Plant Pictures
Female marijuana plants take a bit longer than males to show their first signs after being changed over to flowering.
Female marijuana plants start showing one or two wispy white hairs where their buds are going to start forming.
They usually first show up where the main stem connects to the individual nodes or ‘branches’.
If a female plant is kept in the vegetative stage long enough (the length of time varies depending on the strain and conditions), then she will start showing the first sign of female hairs even before you move the plant into the flowering stage by changing the light schedule.
If you see wispy white hairs appearing on your plant like the ones pictured below, then you know you have a female plant.
Click on thumbnails for larger picture
In this pic, you can see white pistils emerging from the calyxes. Female pistils are white and wispy, never green.
This pre-flower doesn’t have a pistil sticking out at first, but the shape helps tell you it’s a female plant. If you’re not sure about gender after spotting a pre-flower, it’s a good idea to wait and see for a little while, just to see if a white hair appears (which means it’s definitely a girl)
Adult Female Cannabis Plant Pictures
Those buds turn into this!
Male Marijuana Plant Pictures
Male plants have grape-like balls which form and fill with pollen. The balls will first show up a week or two after changing the plants over to the flowering stage. If the male is allowed to continue growing, eventually these pollen sacs will burst open and spill pollen everywhere.
A small male pre-flower – this is what male plants look like when they first reveal their gender
These male pre-flowers are basically immature pollen sacs. When the plant starts flowering, they will grow and turn into bunches that almost look like grapes.
Click on thumbnails for larger picture
Uncertain pre-flower – ended up being female!
Sometimes it takes a day or two for a female pre-flower to release her first pistil, and the female calyx can look like the beginning of a pollen sac. Generally the more “pointy” ones tend to be female, but sometimes you have to wait and see a few more flowers to know for sure.
Marijuana plants go through 2 life stages: Vegetative and Flowering
Quick Key to Light Schedules For Photoperiod (Non-Autoflowering) Strains
This key breaks down some of the terms used in the article below such as “24-0″ or 12-12”
Vegetative – Indoor cannabis plants kept on these light schedules will display only vegetative growth
18-6 – 18 Hours Light / 6 Hours Darkness each Day
24-0 – 24 Hours Light / 0 Hours Darkness each Day
Flowering – Indoor cannabis plants on this light schedule will start growing flowers (buds)
12-12 – 12 Hours Light / 12 Hours Darkness each Day
* Most indoor growers use a timer to turn their lights on and off automatically.
The first stage, “Vegetative” begins when they first sprout, at the beginning of their life.
Most growers give their plants 18-24 hours of light a day during the vegetative stage.
When a plant is about half the final size you want it to be, you should change it over to the “Flowering” stage.
The second life stage, “Flowering,” is the stage your plant will remain in until harvest..
You get marijuana plants start flowering (making buds) by changing your light schedule to 12-12.
That means you use an electric timer to automatically shine your grow lights for 12 hours a day, with 12 hours of uninterrupted TOTAL darkness during the plant’s “night period.”
Marijuana plants should reveal the first signs of their gender within 2-3 weeks after being changed to 12-12.
How Light Schedules Affect Marijuana Life Stages
Marijuana plants have an internal process where they can detect how long they receive uninterrupted darkness each day.
In the wild, as the days get shorter and nights get longer, the marijuana plant “realizes” that winter is coming and will start budding/flowering as it approaches the end of it’s lifecycle.
When growing marijuana outdoors, a grower doesn’t need to do anything to induce flowering because the sun will take care of things on its own. All you need to do is make sure your plant isn’t directly under a street light or other light source, so that the plant receives complete darkness at night.
However, when growing marijuana indoors, a marijuana gardener will have to “fool” their plants into thinking winter is coming to induce flowering and kickstart the creation of buds.
This is done by changing the plant’s light schedule to 12-12, where the weed plants gets 12 hours of light a day and 12 hours of total darkness.
It’s easier to ensure the plant gets the 12 full hours of darkness each night when the start and end time for your lights to turn on and off is exactly the same each day. This is why most growers end up getting a timer to turn their lights on and off automatically.
I tend to set my timer in flowering to shine line from 7pm-7am. This gives me time to check on my plants at night when the lights first come on, and I can also check them quickly in the morning before I go to work. It also keeps things cooler since the lights are on at night. Some people (like myself) also get discounts on electricity that’s used at night.
But ANY 12 hour dark period will work, as long as you prevent your plant from getting light leaks during their “night.”
In fact, with marijuana plants, the length of night period, not the length of day period, seems to make the biggest difference. This makes sense if you consider that in the wild, a stormy or cloudy day could shorten the light period a plant receives, but few things in the wild will interrupt the darkness of night.
This has been experimentally verified by some out-of-the-box thinkers. They gave marijuana plants different amounts of light and dark, then watched what happened.
What they found is that a marijuana plant will stay flowering as long as she gets 12+ hours of darkness on a regular basis. The length of day period didn’t seem to matter at all. In fact, you could give plants 12 hours of dark followed by 24 hours of light, on a regular basis, and plants would continue to flower as long as their darkness was uninterrupted for 12 hours at a time.
Check out my marijuana grow light guide for more info about picking out the right grow lights for your situation!
Photoperiod dependent strains vs. auto-flowering strains
So all strains of cannabis that respond to light in this way (where the light period effects what stage they’re in) are called “Photoperiod dependent” strains.
“Auto-flowering” marijuana strains pretty much ignore how much light they get each day. Generally you don’t run into these unless you buy them particularly from a cannabis seed bank.
Marijuana plants have a gender: Is my plant Male or Female?
(Some marijuana plants can also be hermaphrodites, which means they display both male and female parts on the same plant)
Most growers prefer to grow female plants, as only female plant produce buds/flowers.
Note: Once the plant is about 6 weeks old from seed, it will usually show signs of “pre-flowers” which will alert you to the gender before the beginning of the flowering stage.
Pre-Flowers usually reveal the gender around week 6 from seed, or you can wait until the plant switches to the flowering stage.
After 2-3 weeks of the 12-12 light schedule, most marijuana plants will reveal the first signs of their gender (they either are a female plant and start growing buds, YAY! or they are a male plant and start growing balls, NO!).
Why do I not want male marijuana plants?
Only a female marijuana plant makes flowers/buds that contain a usable amount of THC. Male marijuana plants only make pollen sacs that they use to fertilize the females. Most growers will throw away any male plants that they encounter to keep them from fertilizing the female plants. If your female plants do get fertilized, they will use all their energy to produce seeds instead of making buds. This is good if you want seeds, but you will run into the same problem since half of the seeds will also be male.
If you would like to start a breeding program to make your own hybrids, I recommend using a method that creates all-female (feminized) seeds so that you don’t waste time having to identify and throw out male plants.
Getting clones of female marijuana plants or buying feminized seeds online from a seed bank are other ways you can ensure that all your marijuana plants are female.
If you don’t have a choice of seeds, and some of your seeds may be male (like if you just found seeds) than you will want to get your plants to reveal their gender right away so you don’t have to waste time and energy on male plants.
For most marijuana strains, the male plants don’t produce usable amounts of THC, so most growers toss them on sight. Unfortunately, 50% of all regular seeds will become male plants.
These male plants can also impregnate your female plants, which causes them not to produce as many buds, so unless you’re breeding, destroy male plants as soon as you notice them growing grape-like balls where their buds would normally be.
A vigilant grower can carefully watch their plants and remove males when they develop the first signs of pollen sacs.
How to identify female plants if starting out with regular bagseed?
You don’t have to wait for the flowering stage! Below we’ll share two tactics growers use to identify gender in the vegetative stage.
Tactic 1: Preflowers let you identify plants in week 3-6 from seed
Pre-Flowers reveal the gender of your plant by around week 6 from seed, and as early as 3 weeks from seed for some plants.
In this area you’ll find pre-flowers nestled where the “joints” of the plant are.
Tactic 2: Taking a clone and flowering it
The following method can help you identify gender for plants that are taking a while to show their pre-flowers.
If you’re just growing 1, 2, or 3 plants, it can be heartbreaking to find out all your plants are male, and you need to start over in order to make buds.
When marijuana plants are seedlings (or when they’re just seeds), there’s no way to tell which plants are male and which plants are female.
You have to “wait and see.” Male marijuana plants develop pollen sacs (look like little balls or nuts). Female marijuana plants start growing white hairs that develop into the marijuana buds (sensimilla) that contain THC and other cannabinoids. Lots of pictures of male and female parts above.
However, you may want to be more proactive and get rid of the male plants before they enter the flowering stage so you don’t have to waste the time and energy in caring for plants that you will eventually get rid of. If so, then you can use to following technique to identify and remove all the males from your grow.
How to Determine Sex of a Marijuana Plant
You can wait until your plants naturally show the first signs of their gender and then remove all the males, but that means you have to watch the plants closely. You also will waste time and energy growing plants only to find out that some or all are male and have to throw them away. If you want to be more proactive and get rid of all male plants right away, then use this technique.
Take a clone from the unverified marijuana plant
Label both the clone and the mother plant so you know which clone came from which corresponding mother. If you don’t label them clearly, then all your effort will go to waste!
Once the clones have established roots, change just the clones into flowering mode by providing them with a light schedule of 12 hours on, 12 hours off
The clones should start revealing their gender in a week or two. Males will start developing balls and females will start developing white hairs. Click on the pictures below to see some examples of male and female plants.
Once you have determined the gender of your clones, you should make sure you throw away any corresponding male plants.
Learn about marijuana life stages and gender. When does the plant start flowering? How can you tell if your plant is a boy or a girl? What…