Cannabis seeds are ready to plant and grow once they successfully germinate or once the root has broken through the protective outer shell of the seed. Cannabis seeds are available in regular, feminized, and auto-flowering forms. Home growers of cannabis often choose feminized seeds to ensure that the adult plant will be a flowering female.
Cannabis seeds are brown and about the size of a peppercorn. Photo by: Gina Coleman/Weedmaps
More about marijuana seeds
As with all angiosperms, or flowering plants, cannabis produces seeds that contain all of the genetic information needed for growth and reproduction. When a seed is planted, the translation of this genetic material dictates each unique physical characteristic the mature plant will have. If these are desirable traits, like potency, smell, vigor, etc., a breeder can select for these through a long process of genetic stabilization through generations, which eventually leads to the creation of a cultivar, or strain.
Anatomy of a cannabis seed
Cannabis seeds are about the size of a peppercorn, ovular in form, and pointed on each end with a ridge that transverses longitudinally on only one side from tip to tip. It is this ridge that opens up during germination. The opposite side is rounded. The body of the seed is brown, but underdeveloped and unfertilized seeds can have an off-white color and are typically smaller in size.
Photo by: Illustration by Weedmaps
The body of a marijuana seed is spotted or striped, most commonly with light brown specks, but some varieties of cannabis can have red or yellow markings. Plant embryos are contained within seeds and house all cells that will eventually differentiate into leaves, roots, and stems. Embryos, found within the reproductive organs, are protected by an outer envelope called the pericarp. Crucial components of the plant embryo are the cotyledons, the first leaves to appear from the seed, and the radicle, which develops into the primary root. Once the seed germinates and begins its growth into a mature plant, special structures called root caps protect the growing tips of the plant.
Today’s commercially cultivated cannabis does not contain seeds. The cultivation practices that have made this widespread are rooted in fundamental biological concepts. Cannabis is a dioecious plant, meaning it has separate male and female organisms, just like humans. If a female plant matures in the presence of a male plant, pollen from the male will fertilize the female, and its bracts will contain seeds at the end of the flowering cycle. Seedless cannabis is commonplace even when it originates from mass-produced outdoor cultivation, but not too long ago, this was not the case.
Around the middle of the 20th century, growers discovered that culling male plants as soon as they display their sexed traits would result in a crop containing exclusively unfertilized females, yielding cannabis flowers higher in THC that don’t require the removal of seeds before smoking. This seedless cannabis was from then on dubbed sinsemilla, which translates to “without seed” in Spanish. It is also commonly spelled sensimilla.
How cannabis seeds are produced
Commercial growers who produce cannabis flower desire seedless plants but there are also cultivators interested in selling seed to the growing home-cultivation market. Cannabis seed production begins with the pollen grain of a male plant. From this grain, a pollen tube grows, producing male generative cells that disperse in the form of pollen. The migration of pollen into a female plant ovule triggers pistils to fall off and seed production to begin. The bracts, which contain the ovule, will then fill with seeds. Since seeded plants are a natural outcome of pollen fertilizing eggs, producing cannabis seeds is a matter of letting nature take its course.
What’s the difference between feminized, regular, and autoflower seeds?
There are a few differences to note between these cannabis seed types.
- Feminized seeds: The key difference between feminized cannabis seeds and regular cannabis seeds is that feminized seeds have been engineered to produce exclusively female plants. This matters for cultivation since smokable flowers are produced only by female plants. A male plant can potentially ruin a harvest if it pollinates nearby female plants, causing them to produce flowers full of seeds.
- Autoflowering seeds: Autoflowering seeds have been carefully bred to begin and complete the flowering process based on the plant’s maturity rather than how much light the plant receives each day. Autoflowering seeds tend to be simpler to grow and don’t require as much light, making them perfect for places where the growing season is short or for indoor grows.
Is it illegal to buy marijuana seeds?
Marijuana seeds are a cannabis product, so if you live in a place where cannabis is illegal, then seeds are also illegal. However, some people who live in places where weed is not yet legal purchase marijuana seeds from marijuana seed banks as a “souvenir.” Either way, if you want to buy marijuana seeds and cannabis is illegal where you live, then you face some degree of risk. On the other hand, if you live in a state where cannabis is legal, especially one where home cultivation is allowed, then you should be able to purchase seeds legally. Remember, even in states where cannabis is legal, it’s still illegal nationally in the US. To cut your risk as much as possible, purchase cannabis seeds from in-state or local providers so they don’t have to cross state lines or be transported by mail.
Where to buy marijuana seeds
Seeds are sold in brick-and-mortar locations legally in many countries across Europe and are often traded online. As cannabis legalization expands in North America, more retail locations are carrying seeds as well. Feminized seeds are the most popular, but providers likely have access to many strains of mixed male and female seeds. Carefully sifting through cannabis flower before using the grinder will usually turn up a few seeds, too. Professionally sourced seeds assure quality genetics and viability, but saved seeds can be a cheap source of cannabis genetics for the hobbyist grower.
Do dispensaries sell seeds?
If you live in a state or country where cannabis is legal, and where individuals are allowed to grow their own plants at home, then you should be able to buy seeds at most legal dispensaries. This might not be the case if you’re in a location that does not allow home growing. The best thing to do is simply check your local laws and ask your local budtender.
How much do marijuana seeds cost?
A pack of marijuana seeds—typically containing around ten or so seeds—will run you anywhere from around $40 on the low end and as much as $400 or $500 on the upper end. The price of marijuana seeds depends on a number of variables including:
- Quality of genetics
- The reputation of the breeder who produced the seeds
- How rare or potent the strain is
- Whether they’re regular, feminized, or autoflowering (feminized and autoflowering marijuana seeds tend to cost more)
How many seeds should I buy?
If you’re trying to grow just a handful of plants for your own private consumption, then you can get away with purchasing one or two packs at a time. Since most commercially sold marijuana seeds come in packages of 10 or so seeds, 10 to 20 seeds should be enough to ensure a good harvest even if a few seeds fail. This is a baseline for a small, private crop andany larger operations should scale up accordingly.
How to store cannabis seeds
Seed providers sometimes vacuum-seal and freeze seeds for long-term storage, but commercially-available seeds in Dutch headshops are sold in small, plastic vials at room temperature and low humidity (6-12%).
Humidity and light is the main enemy of seed storage. Beyond that, seeds can remain viable for up to two years when stored in even the most haphazard conditions. Marijuana seeds swept up off the floor or found in the bottom of a drawer have been known to grow into vigorous young plants.
Germinating cannabis seeds
Germination is the process of beginning the vegetative growth of the new cannabis plant. Sometimes referred to colloquially as “popping,” this process starts when the seed is exposed to water and light. The seed abandons its state of dormancy, or quiescence, and resumes essential metabolic processes that feed on energy stores to delicately rupture open the shell and grow its first root. This root will elongate until it has taken hold of the medium, after which it will pull two small embryonic leaves (cotyledons) from the seed shell. Cotyledons are in the seed before germination and are not considered “true” leaves. The cotyledons will grow until they are about one centimeter long, and once the stem below this is around five centimeters tall, another set up true leaves will grow out of the top and the stem between the true leaves and cotyledons will continue to elongate.
Photo by: Gina Coleman/Weedmaps
Generally speaking, cannabis is a hardy plant that will grow and even thrive in a diversity of environments. However, to assure germination, several steps can be taken. One method calls for a moist paper towel inserted into a plastic bag. Once the first root appears, the seedling must be carefully transferred to some soil before the root takes hold to the paper towel.
Cannabis seeds can also be germinated in a peat pellet. Plant the seed only just below the surface. Once the seedling has taken hold in the pellet, directly transfer it to a pot; the roots will grow right through the soft fabric that encases the peat, at which point the pellet can be directly placed into soil. Whichever method is used, keep the temperature between 70 -90 degrees Fahrenheit (21-32 degrees Celsius), ideally at 78 degrees Fahrenheit (about 26 degrees Celsius), keeping seedlings covered to maintain humidity. Seedlings and young cuttings require photosynthetically active radiation that is more heavily weighted in the blue portion spectrum; a common fluorescent desk lamp will suffice until they are about 5 inches, or about 13 centimeters, tall.
Can You Tell if a Cannabis Seed is Male or Female?
W hen it comes to growing cannabis, sex is important. Not that kind of sex! We’re talking about the sex of the plant, and whether it is male or 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.
- Cannabis Seeds Explained
- What to Look for When Buying Cannabis Seeds
- How to Germinate a Bag Seed
- Understanding the Anatomy of a Cannabis Plant
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 as they grow, and flowers that have not been pollinated are much more likely to produce high-potency cannabis. This is the basis of all modern medical and recreational cannabis cultivation, so determining the sex of a plant is highly important. But is there a way to know if a seed is female before growing?
Table of Contents:
- Determining if a Cannabis Seed Is Male or Female
- What Are Feminized Cannabis Seeds?
- Methods for Feminizing Cannabis Plants
- Separating Male and Female Cannabis Plants
- How Important is Your Plant’s Sex?
Determining if a Cannabis Seed Is Male or Female
The straightforward answer is that, if what you’ve got is a handful of unmarked seeds, it’s pretty much impossible to tell which ones are male or female. The only true way to tell the plant’s gender is to plant a seed, then wait for it to mature.
After a period of several weeks, the plant 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. Male plants will instead produce pollen sacs that look rounded with distinct splits running lengthwise, a bit like a tiny crab claw. These are the structures that growers typically look for to determine a plant’s sex.
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 folks that aren’t 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 Cannabis 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 quite popular. Feminized seeds are selectively bred to produce only female plants.
While the process is very effective, it’s not perfect. There’s a chance that a small fraction of the seeds produced via the feminization method will sprout hermaphrodites, which are still capable of producing pollen.
Despite the potential for ‘hermies,’ 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 a 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.
Separating Male and Female Cannabis Plants
As anyone with seasonal allergies can attest, it only takes a little bit of pollen to have a big impact. The reason that growers are so intent on weeding out male cannabis plants is that a single pollinator can negate an entire potential harvest.
How? The reason is that once pollinated, cannabis plants will cease devoting energy to growing flowers and will tell the existing flowers to stop producing resin, which translates to making less buds and less THC. That energy will be devoted to producing seeds instead. Think of the plant as a battery with a set amount of power. When that supply is spent in one area, it won’t be available for another.
Now consider that a single male plant can spread its pollen to an entire room of females.
If a grow is accidentally pollinated, that means the resources that were spent to bring the plants to that stage — the water, soil, electricity, fertilizers, not to mention the price of the seeds themselves — will have been wasted growing weed that can’t be smoked.
All of those male plants will have to be carefully separated from the grow space and destroyed, or else the growers risk another disastrous accidental pollination. It takes minuscule amounts of pollen to pollinate a plant, so growers must take extensive precautions to eliminate potential contamination. In addition to helping mitigate other contaminants, this is one of the main reasons that many workers will don full-body suits when working in a grow room, ensuring that accidental pollen exposure is kept to a minimum.
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 to keep a reliable supply, buying feminized seeds from a trusted seller is the way to go. It may even be worth it to have your plants tested for sex before they mature. However, 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.
Erin’s work and industry insights have been featured on the podcasts The Let’s Go Eat Show, In the Know 420, and she has appeared as a featured panelist on the topic of hemp media. Erin has interviewed top industry experts such as Dr. Carl Hart, Ethan Nadelmann, Amanda Feilding, Mark A.R. Kleiman, Dr. James Fadiman, and culture icons Governor Jesse Ventura, and author Tom Robbins. You can follow her work on LinkedIn, WordPress, @erinhiatt on Twitter, and @erinisred on Instagram.