How to Sex Marijuana Seeds: Myths and Facts
Contents
- Understanding the Basics
- Can You Sex Marijuana Seeds?
- How to Determine the Sex of Cannabis Seeds
- The Most Common Misconceptions About Sexing Marijuana Seeds
- The "Cracking" Myth
- Size and Shape Indicators
- Gender-Identifying Colors
- Conclusion
- FAQs
- Can I tell the sex of a cannabis seed by its appearance?
- When can I determine the sex of my cannabis plants?
- Sources
Many new growers want to know how to sex marijuana seeds. Female plants produce the resin-rich buds, while males produce pollen that leads to seeded buds.
Here's the short answer: you can't tell a seed's sex by looking at it. Size, shape, color and how hard the shell feels tell you nothing about whether it will grow into a male or female plant.
Understanding the Basics
Every seed already carries the genes that set its sex. You just can't see them from the outside.
Cannabis is usually either male or female, but some plants develop both male and female flowers. These plants are called hermaphroditic.
Sex is decided by chromosomes. Female cannabis plants typically have two X chromosomes (XX), and males have an X and a Y (XY).
A review of feminized seed production in Frontiers in Plant Science explains that feminized seeds come from a female plant crossed with female pollen, so they carry XX chromosomes and should grow into females.
Growers care because female plants produce the flower buds rich in cannabinoids. Male plants produce pollen, which fertilizes females and makes them produce seeds instead of seedless buds.
Photo by Rickproser (talk), CC BY 3.0, via Wikimedia Commons
Can You Sex Marijuana Seeds?
Not by looking. A seed's sex is in its genes, and nothing about its outside shows it.
So, you can't sex marijuana seeds by eye. You find out once the plant grows and shows its first flowers.
If you want only females, buy feminized seeds from a reputable breeder.
How to Determine the Sex of Cannabis Seeds
The only practical way for home growers is to germinate the seeds and grow the plants until they show their sex.
This applies to regular and feminized seeds alike. Feminized seeds are expected to grow into females, but it is still worth checking.
The first leaves, called cotyledons, look the same on males and females.
As the plant grows, it develops nodes, where leaves and branches meet the stem. Small pre-flowers appear at these nodes once the plant is mature enough, often several weeks into vegetative growth.
Female pre-flowers have thin white hairs (pistils). Male pre-flowers look like small round balls (pollen sacs). We cover this in detail in our guide to the differences between female and male cannabis plants and how to sex them.
The Most Common Misconceptions About Sexing Marijuana Seeds
There are plenty of myths about telling male and female seeds apart. None of them work.
The "Cracking" Myth
Some growers believe female seeds crack open more easily than male seeds when pressed.
This is a myth. How easily a seed cracks depends on its maturity, age and storage, not its sex. Pressing seeds can also damage them.
Size and Shape Indicators
Some believe larger seeds are more likely to be female and smaller seeds male. There is no evidence for this.
Seed size and shape vary with genetics and growing conditions, not sex.
Gender-Identifying Colors
Another myth says darker seeds are female and lighter seeds are male. Again, there's no scientific basis.
Seed color mostly reflects genetics and maturity. Pale seeds are often immature, but color doesn't predict sex.
Conclusion
You can't sex marijuana seeds by their appearance. The sex is set by their chromosomes, and you find out only once the plant starts to germinate, grows and shows pre-flowers.
If you want female plants without the guesswork, start with feminized seeds and still check your plants as they mature.
Grow only where home cultivation is legal for adults. Marijuana remains a Schedule I drug under US federal law outside narrow exceptions, and state laws differ.
FAQs
Can I tell the sex of a cannabis seed by its appearance?
No. Regular and feminized seeds look alike, and size, shape and color don't reveal sex.
When can I determine the sex of my cannabis plants?
When pre-flowers appear at the nodes, which is often several weeks into vegetative growth.
Sources
- Optimized guidelines for feminized seed production in high-THC Cannabis cultivars, Frontiers in Plant Science (via PubMed Central)
- Cannabis (Marijuana) and Cannabinoids: What You Need To Know, NCCIH
- Schedules of Controlled Substances: Rescheduling of FDA Approved Products Containing Marijuana From Schedule I to Schedule III, Federal Register (U.S. Department of Justice, DEA)
