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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.

Cannabis seeds 101: A guide for growers

Cannabis is grown from one of two sources: a seed or a clone. Seeds carry genetic information from two parent plants that can be expressed in numerous different combinations, some like the mother, some like the father, and many presenting various traits from both. Generally, commercial cannabis producers will plant many seeds of one strain and choose the best plant. They will then take clones from that individual plant to get consistent genetics for mass production.

But for the typical homegrower, it may be easier to obtain seeds rather than clones. Growing from seed can produce a stronger plant with more solid genetics. Read on for more info on cannabis seeds.

Check out these additional resources for more info on cannabis seeds:

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What are cannabis seeds?

Cannabis can be either male or female—also called “dioecious”—but only females produce the buds we all know and love. However, for reproduction, the flower of a female plant must be pollinated by a male plant, after which the female flower produces seeds.

Once the seeds are mature, the female plant begins to die, and seeds are either dropped to the ground where they germinate and grow into new cannabis plants the next spring, or they are harvested for processing into seed oil, food products, or to be sown to become the next generation of plants.

To get the buds you find in medical and recreational stores, female cannabis plants are grown in an environment without males—or the males are removed from the area before they release pollen—so that the females don’t create seeds. This high-potency marijuana is traditionally known as “sinsemilla,” meaning “seedless.”

Some varieties of cannabis can produce male parts alongside female flowers on the same plant, especially if exposed to environmental stressors. These plants are known as hermaphrodites, and sometimes they can self-pollinate to create seeds.

What are feminized cannabis seeds?

Feminized cannabis seeds will produce only female plants for getting buds, so there is no need to remove males or worry about the plants getting pollinated. Feminized seeds are produced by causing the monoecious, or hermaphrodite condition in a female cannabis plant. The resulting seeds are nearly identical to the self-pollinated—or “selfed”—female parent, as only one set of genes is present.

This is sometimes referred to as “cloning by seed” and will not produce any male plants. This is achieved through several methods:

  • By spraying the plant with a solution of colloidal silver, a liquid containing tiny particles of silver
  • Through a method known as rodelization, in which a female plant pushed past maturity can pollinate another female
  • Spraying seeds with gibberellic acid, a hormone that triggers germination (this is much less common)

Most experienced growers will not use feminized seeds because they only contain one set of genes, and these should never be used for breeding purposes.

Check out Leafly’s Growing section for more on how to grow cannabis

What are autoflower cannabis seeds?

Most cannabis plants begin flowering when the amount of light they are exposed to each day is reduced to about 12 hours. This mimics the sun going down in the sky as the season turns to autumn.

However, a species of the plant, called Cannabis ruderalis, which developed in extreme northern conditions without much sunlight, will begin flowering once the plant reaches a certain age—they automatically start flowering regardless of the amount of light they receive, hence the term “autoflower.”

Some breeders have crossbred the low-THC ruderalis with other more potent varieties to create autoflower strains that start blooming as soon as they reach maturity. These can be easier to maintain and can be especially great in northern climates where summers are short and cold, wet weather comes early in the fall.

Autoflower strains can be started in early spring and will flower during the longest days of summer to take advantage of the highest quality light available. Growers can fit in multiple autoflower harvests in the span of a regular harvest.

One drawback, though: Autoflower strains are known for being less potent.

What are high-CBD cannabis seeds?

Cannabidiol, or CBD, is one of the chemical components—known collectively as cannabinoids—found in the cannabis plant. Lately, much has been made of the potential benefits of CBD for treating the symptoms of many diseases and conditions. Over the years, humans have selected plants for high-THC content, making cannabis with high levels of CBD rare. The genetic pathways through which THC is synthesized by the plant are different than those for CBD production.

Cannabis used for hemp production has been selected for other traits, including a low THC content, so as to comply with the 2018 Farm Bill. Consequently, many varieties of hemp produce significant quantities of CBD. As interest in CBD as a medicine has grown, many breeders have been crossing high-CBD hemp with cannabis. These strains have little or no THC, 1:1 ratios of THC and CBD, or some have a high-THC content along with significant amounts of CBD (3% or more).

Seeds for these varieties are now widely available online and through dispensaries. It should be noted, however, that any plant grown from these seeds is not guaranteed to produce high levels of CBD, as it takes many years to create a seed line that produces consistent results. A grower looking to produce cannabis with a certain THC to CBD ratio will need to grow from a tested and proven clone or seeds.

What makes a cannabis seed high quality?

The most important factor in seed quality is genetics—to grow quality cannabis, you need good genetics. Some less scrupulous breeders will simply cross a nice female with a random male and sell the resulting seeds. A good breeder will take time to cross and backcross plants to stabilize the most desirable traits, while still producing an array of different phenotypes.

Seeds must also be allowed to fully mature before harvest. They also must be properly stored so they don’t acquire mold or other pathogens that can spoil them. Seeds should be stored in a cool, dark place and used within 16 months, or frozen for future use.

Really dedicated breeders have worked for years to create inbred lines, or IBLs, that will produce plants with very little noticeable difference. IBLs represent only a small fraction of cannabis seeds on the market, as they are generally used by breeders and not by producers.

Where can I buy cannabis seeds?

Cannabis seeds can be found on numerous online seedbanks, but note that it is illegal to bring seeds into the US and Customs will seize any cannabis seeds that they find in packages or on a person. In legal and medical states, you may purchase seeds at a dispensary.

Learn more about how to buy cannabis seeds, the legality of doing so, and costs in our Guide to buying cannabis seeds.

This post was originally published on April 2, 2016. It was most recently updated on February 5, 2020.

Learn the basics about cannabis seeds, such as what they are, what "feminized" and "auto-flowering" means, seeds vs. clones, and more. ]]>