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Plant problems · 8 minute read · Updated October 15, 2026

Hermaphrodite cannabis and nanners: spot them, then act

Short answer. A hermaphrodite (intersex) cannabis plant is a female that also grows male parts: either round pollen sacs at the nodes or bare yellow stamens called nanners poking out of the buds. In one university study they showed up on 5 to 10 percent of plants in three commercially grown strains, usually from about week 4 of flower. A few late nanners can be plucked out with clean tweezers; a plant covered in open pollen sacs should leave the tent before it seeds everything around it.

One yellow banana in week 7 can put seeds in buds you spent four months growing. The question is not whether you will ever see one. It is whether you will see it on the day it appears, or the week after it opens.

What a hermaphrodite cannabis plant actually is

Most cannabis plants are one sex or the other. Females carry two X chromosomes and males carry an X and a Y. You want females, because their unpollinated flowers are the resin-heavy buds you harvest.

A hermaphrodite, which researchers more often call an intersex plant, is a female that also makes male flower parts. Those parts can shed pollen. Pollen that lands on a receptive pistil makes a seed, and the plant spends energy filling that seed instead of building bud.

It happens more than many growers expect. Researchers at Simon Fraser University examined plants of three strains grown commercially indoors and found male flower parts on 5 to 10 percent of the plants. In roughly 1,000 plants they also found two where an entire bud had turned into anthers. That is not a rare freak event. In a tent of four plants, the odds that you meet one at some point over several grows are real.

So the useful question is this: how often are you actually looking inside your buds after week 3 of flower?

Nanners vs pollen sacs: the two forms you will see

Intersex parts show up in two main forms, and they call for different responses.

The two forms of male parts on a female plant
FormWhat it looks likeWhereHow risky
Nanners (exposed anthers)Small pale yellow or lime "bananas", often in clusters, poking out between the pistilsInside or on the surface of buds, usually mid to late flowerLower if caught early, but they can release pollen
Pollen sacs (male flowers)Round green balls on short stalks, often in clusters, with no white hairsAt the nodes where branches meet the stem, sometimes deep in the plantHigher: a full flower can open and dust the whole tent

In the Simon Fraser study, the anther clusters inside buds were bright yellow and about 2 to 3 mm long, tucked against the bracts right next to the stigmas. Under a microscope each anther had a seam that splits to release pollen, the same as on a male plant. The pollen was alive: 10 to 30 percent of it germinated in the lab.

One honest note from the same study: these anthers released far less pollen than a true male flower does. That is why a handful of nanners is a smaller emergency than a branch of open pollen sacs.

Things that look like a hermie but are not

Before you pull a plant, make sure you are looking at male parts. Three lookalikes fool new growers all the time.

Use a 30x to 60x jeweler's loupe or a phone macro lens. A clear photo also lets you compare the same spot two days later, which settles most doubts.

What causes hermaphrodite cannabis? What the research shows

Here is the part most grow guides get wrong: they state the causes with total confidence. The science is thinner than that.

The 2020 Simon Fraser paper says it plainly: the factors that trigger the change have not been studied much. What is known falls into three groups.

  1. Genetics. Some plants carry a stronger tendency than others. That is why the same stress can hit one plant in the tent and skip the next. Breeders select against it for this reason.
  2. Chemistry and hormones. Silver compounds that block the plant hormone ethylene reliably make female plants grow male flowers. Seed makers use silver thiosulfate this way on purpose to make feminized seed: the pollen comes from a female, so the seeds carry only X chromosomes.
  3. Environmental stress. Earlier reports, summarized in the 2020 paper, link short photoperiods, cooler temperatures and long darkness to more male flowers. Grow books add light leaks during the dark period, timer failures, heat and rough handling. These are widely reported by growers but have not been tested one by one in controlled trials.

So treat stress as a risk you lower, not a switch you can flip off. A stable plant in a stable room is less likely to surprise you. An unstable plant can still do it in a perfect room.

If you grow photoperiod plants, the dark period is the stress you control most directly. Our guide to light leaks and light schedules shows how to find and fix them in ten minutes.

When nanners show up and why timing matters

In the Simon Fraser plants, stigmas were most receptive around weeks 3 to 4 of flowering. Anthers inside the buds appeared from about week 4, stayed visible through weeks 4 to 7, and were still there at harvest. Seeds made in that window were fully mature in the bud before harvest, and 90 to 95 percent of them sprouted.

That gives you a simple rule: from week 3 of flower until the chop, inspect every plant every two or three days. Look at the tops, then pull the canopy apart and look at lower nodes, where pollen sacs hide.

How bad is a seeded bud? In that study, single buds that had seeded held 22, 34 and 48 seeds. Each seed is weight the plant put into reproduction instead of resin and flower.

What to do when you find one

Your response depends on what you find and how close you are to harvest. Stay calm and work through it in order.

A few nanners, late in flower

Pollen sacs at the nodes, or many nanners in early flower

What not to do

How to lower the odds next grow

You cannot make the risk zero, but you can stop handing your plants extra reasons.

That last point is where a journal pays off. In Canna GLAP you can log the date and a photo against the exact plant and look back at your sensor readings for heat spikes in the days before. Our post on how to keep a grow journal covers what else is worth writing down.

Autoflowers, feminized seed and hermies

Feminized seed is made by forcing a female to produce pollen, so some growers worry those seeds are more prone to intersex flowers. Some grow books say so. We found no large controlled trial that settles it. What matters most is the stability of the specific line.

Autoflowers do not depend on a dark period to start flowering, so light leaks are a smaller trigger for them. They can still show intersex flowers from genetics or other stress. If you are choosing between the two types, see autoflower vs photoperiod.

Questions growers ask

Can you smoke buds from a hermaphrodite cannabis plant?

Yes. Buds from an intersex plant are still cannabis. The main loss is seeds in the buds and lower yield where pollination happened. Pick the seeds out when you trim.

Will one nanner seed my whole tent?

Usually not. Nanners inside buds release far less pollen than a true male flower, so a few plucked early tend to cause a few seeds, if any. Open pollen sacs at the nodes are the bigger threat to nearby plants.

Do light leaks cause hermaphrodites?

Grow books and many growers report it, and research lists long darkness and short photoperiods among reported triggers, but light leaks have not been tested as a cause in controlled trials. Stray light is proven to delay or disrupt flowering, so fixing leaks is worth doing either way.

Are seeds from a hermie plant all female?

In one 2020 study, seedlings grown from intersex plants all tested female by DNA marker, but only small numbers were tested: at least 15 seedlings in each of two strains. They also inherit a parent that showed the trait, so they are not a clean line.

When do nanners usually appear?

In the study that tracked them, from about week 4 of flowering onward, staying visible through week 7 and until harvest. Check every two or three days from week 3.

Read next

Sources

Education only, for adults 21+ where home cultivation is legal. Updated October 15, 2026.