Hermaphrodite Cannabis Plants: Causes, Signs and Prevention

A hermaphrodite cannabis plant, or "hermie," is one that grows both male and female flowers at the same time. It can happen naturally or be triggered by stress, from light leaks and heat to rough handling. If you catch it, pluck the male flowers or pull the plant before its pollen seeds your harvest.

Hermies have two main causes: environmental stress or a genetic tendency:

1. On the genetic side, some strains are more prone to herming than others. That can come from the strain's genetic background (feminized strains, for example, can carry a stronger tendency to hermie) or from the technique used to make the seeds.
2. As for stress: when the plant senses that flowering conditions are rough, going hermie becomes its most natural way to cut the cycle short, letting pollen from a few male flowers fertilize the female ones. Stress can come from a bunch of places:

• Light leaks during flowering: changes to the photoperiod, especially interruptions to the dark period in bloom.
• Temperature swings: heat that runs too high (above roughly 27 °C / 81 °F) or the wrong climate conditions overall.
• Harvesting way too late.
• What's known as mechanical stress: branches broken by outside causes, roots damaged during a transplant, pruning in the middle of flower, and so on.
• Bad watering can hit plants hard too, meaning either too little or too much.
• Big swings in pH, or too much fertilizer or PK booster
• Insects, mites or diseases
• Temperature shock when watering (for example, water that's too cold)
• Using phytotoxic products (ones that burn or damage the plant)

If you've got several hermaphrodite plants in your garden, the cause is most likely environmental. If it's just one, genetics is the likely culprit. Some strains just tend to go hermie. Doing a little homework on the strain you want to grow helps you steer clear of them. Your best bet is to start from one of the many cannabis strains with stable genetics.

How can you tell if a cannabis plant is a hermaphrodite?

If you found seeds in your harvest and there were no male plants anywhere near, we've got bad news: at least one of your plants was a hermie. The male flowers that didn't get pulled dropped their pollen on the female plant. Sadly, once plants are fertilized, they start putting their energy into making seeds instead of new flowers.

Worse, seeds from hermaphrodite plants carry a strong tendency to hermie themselves, so we don't recommend growing them out.

How do you prevent hermies?

The most important thing you can do to prevent hermaphrodite cannabis is to stress your plants as little as possible during flowering. With that in mind, we recommend doing all your pruning and staking during veg and early flower (the stretch), before the buds start to form.

We also recommend:

Keep your grow clean and conditions dialed in:

Your grow space needs a stable climate and spotless hygiene. Check your timer regularly, keep an eye out for insects and mites, and make sure feeding and watering fit what the plant needs. Toward the end of flowering, check the trichomes often so you don't blow past your harvest date.

Pick the right strain:

When you're choosing strains for your next grows, read other growers' reports on those genetics and on the seed banks that sell them, so you can avoid strains known for herming.

It's also worth looking more closely at regular cannabis seeds, which are known to be a bit less prone to herming than feminized seeds.

What should you do if you find a hermaphrodite cannabis plant?

Once flowering starts, stay alert. Check your female plants as often as you can for any male parts. But how do you tell a male plant from a female? How do you know if it's female or male?

Male cannabis plants show their sex with little balls (the male flowers), which release pollen once they open. Female plants, on the other hand, show bright white stigmas, or pistils, on their stems and shoots; you'll notice they look like short, thick little hairs. Either way, to sex your plants you'll need to wait until they've grown and start showing, as we explain below.

In full flower, male parts stand out thanks to their bright yellow color and their shape, like tiny bananas (growers call them "nanners"). So if a plant shows both female and male flowers from the start of bloom, you'll need to pull it right away.

If the plant goes hermie in the middle of flowering, you've got 2 options:

1. If it's only throwing a few male flowers, you can try plucking them off with tweezers, misting the plant with water first to keep pollen from flying, and then checking every day for new ones. If it's producing lots of male flowers, the plant has to go.
2. If a plant turns hermie at the very end of flowering, harvest it before the male flowers release their pollen.

Tips to avoid seeded buds

Environmental and growing conditions are much easier to control indoors, so an indoor grow can help you avoid hermaphrodite flowers. The big problem a hermie flower creates, indoors or outdoors, is pollination. If you're after seedless female buds, you'll need to pull hermaphrodite plants from the grow, same as you would with male plants.

So the only real way to keep a hermie from showing up in your grow is to keep tight control of your grow room and all its environmental and growing factors. 

A hermaphrodite cannabis plant can still give you buds, and even with seeds in them, it beats nothing. If you've got the room, there's no risk of pollinating other female plants,  and you're willing to see the plant through to the end, it's worth keeping. On top of that, a hermaphrodite cannabis plant can also be used to make hash, edibles or other extracts, just like male plants. 

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