Sexing marijuana plants is a crucial part of the growing and breeding process. Cannabis plants are generally dioecious plants, which means that they will produce either female or male reproductive organs. In certain environmental conditions, however, cannabis plants can be monoecious, also known as “hermaphroditic.” Monoecious plants feature both male and female reproductive organs.
When growing from seed, growers keep a close eye on early plant growth to make sure they know which plants are female and which are male. Knowing the difference between the sexes tells growers whether the plant will be used to grow trichome-rich and dense flower buds or to produce exciting new genetics. If you’re exercising your green thumb with cannabis plants, here’s everything you should know about sexing marijuana plants as early as possible.
When cannabis growers obtain a marijuana clone, the clone will have the same sex as its mother. However, cannabis grown from seeds, even those advertised as “feminized seeds,” requires careful attention during their growth phase. There is a strong likelihood that as many as half of your marijuana seeds will grow into male plants. If you’re trying to grow female flower buds to their maximum potential, male plants can ruin a harvest when they distribute pollen.
A single male marijuana plant can pollinate an entire cannabis grow operation. Some experts even recommend a minimum distance of 10 miles between outdoor marijuana fields to avoid cross-pollination. Marijuana pollen can reach even further than that, but the risk is drastically lowered. Marijuana pollination is an important part of breeding new hybrid and stable genetics. While commercial breeding operations use hundreds of plants and hunt for the most desirable phenotypes, home growers are generally limited to small-batch breeding by government cultivation limitations.
If a female marijuana plant gets pollinated, it stops growing flower buds and switches to seed production. Non-pollinated female plants are also known as sinsemilla, meaning “without seeds.” These plants produce the most terpene- and cannabinoid-rich flower buds. Removing male plants from the garden as soon as possible keeps your female crop intact and growing flowers.
Sexing Marijuana Plants
In order to determine the sex of your marijuana plant, you’ll need to pay close attention to the area of the plant where sexual organs grow. A cannabis plant’s sexual organs grow at the nodes, where the base of the leaf stalk (petiole) attaches to the main stem Growers should use a 10x loupe or hand-held magnifying glass to locate and monitor stipules at these nodes. Stipules resemble two narrow spikes, one on either side of the node. Examine the node region every day for calyxes emerging from the stipules.
- If the calyx is raised on a small, short stem, and staminate primordia (small sacs) are growing between the nodes, it’s probably a male plant.
- If pistillate primordia (two fuzzy white hairs) are growing between the nodes and the calyx is not raised on a small short stem, it’s a female plant.
Growers can get a good idea of whether a plant is male or female earlier in the flowering cycle, even without seeing the reproductive organs. If seeds of the same strain are planted at the same time, the difference in sex will usually manifest in different heights. Female plants tend to grow shorter and bushier compared to male plants. Female plants also have a larger number of leaves near the top than males (where flowers will form).
As you grow more plants, you’ll learn to determine the sex of your plants during the vegetative stage of growth. Novice growers may take a few weeks longer to determine the sex of the plant. You should be checking the nodes every day for calyxes growing from the stipules. At the very latest, plants will show their sex two or three weeks after the light schedule is switched to 12 hours of light and 12 hours of darkness each day.
Removing Male Plants
Remove male marijuana plants as soon as you determine their sex. Male marijuana plants produce a scant number of flowers with very low THC levels. Still, there are many great uses for male cannabis plants. Instead of discarding your male plants, here are a few ways to make the most of them:
- Breed new genetics by pollinating select female plants.
- Juice the leaves of male cannabis plants or put them in a salad.
- Extract cannabinoids from male plants’ leaves, stems, and sacs to produce concentrates.
- Use the soft hemp fiber produced by male plants to make clothing and other textiles
Sexing marijuana plants gets easier the more times you do it. At first, you may have trouble identifying the distinct characteristics of the cannabis plant’s male and female reproductive organs, but daily observation helps you catch those male plants early.
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