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.
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.
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.
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.
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.
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.
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?
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.
Although this plant ended up being male, the stipules are long, pointy and crossed as you’d normally see with a female plant. That’s why you need to confirm sex with the pre-flowers and not just look at other factors on the plant!
What you’re looking for is “pre-flowers.” These are tiny versions of adult sex parts, and when you see them you can tell what sex the plant is going to be. They usually show up in the upper parts of the plant, closer to the lights, but sometimes you’ll search the whole plant and only find a pre-flower on a random branch lower down on the plant.
Female pre-flowers tend to be longer and narrower than male pre-flowers, sometimes with a fat bottom. They also usually (but not always) have 1-2 white hairs (pistils) sticking out from the top. Sometimes it takes a few extra days for the pistils to appear.
Variability of Cannabis Plant Sex – How to Increase Ratio of Female Plants with Regular Seeds
Chemical leaf testing is getting less expensive every day and can be used on cannabis seedlings with just a few sets of leaves to test for sex and future potency.
This is the exact same picture as above, but with the pre-flower made bigger so you can see it. Pretty tiny, isn’t it?
Did You Know? There are Chemical Leaf Tests that Can Definitively Determine Both Plant Sex & Future Cannabinoid Ratios of Very Young Marijuana Seedlings!
Once you see multiple pollen sacs and no white pistils, you can be confident it’s a male plant
We know that determining the sex of cannabis seeds cannot be done. However, it’s unclear as to whether environmental factors have any place in determining the sex of marijuana plants.
So where do all the myths from sexing cannabis seeds come from?
MSNL Team / 19th July 2018
Common myths on identifying the sex of a cannabis seed
This has been a question that has become a very hot topic online these days. After a quick search, growers can find multiple charts and explanations on how to sex cannabis seeds.
This same chart states that females will also roll easily across a table or surface, while males will not. While it does say that a magnifying glass and pair of tweezers is needed to examine the seeds. neither of these tools will make it any easier to determine the sex of cannabis seeds.
Unfortunately, there’s not much truth to any of these interpretations. It’s simply impossible to tell just by looking at them what the sex of any cannabis seed is. If it was that easy, feminized marijuana seeds would not be as popular as they are. People could simply buy regular seeds and look at them themselves.
Research is carried out all the time to determine if a plant’s environment has anything to do with the sex it will turn out to be. And while there’s research stating that it does not, there’s just as much research stating that certain species do have their sex determined by the environment. This same research also states that using certain chemical treatments can also reverse the sex of a plant.