How to Identify a Swollen Calyx vs a Pollen Sac/Hermie Plant

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The best time to harvest cannabis plants, most growers will attest, is immediately after the calyxes have swollen. Identifying when this has occurred, however, can prove more difficult than it may seem.

To make matters worse, many similarities exist between swollen calyxes and pollen sacs, making it easy to mistake one for the other. Since pollen sacs are an indications of a hermaphrodite plant, meaning a plant likely to develop pollen sacs inside its buds, making this mistake can be to the detriment of cannabis growers.

Fortunately, there are ways to distinguish a swollen calyx from a pollen sac, as long as you understand what each one is and know what to look for.

About Calyxes

A calyx is the initial part of the flowers forming on a cannabis plant. Calyxes first appear when a young cannabis plant begins its flowering phase.

Of course, the plant must be able to flower in order for any calyxes to appear, which means, on cannabis, calyxes only appear on female plants. By contrast, since male cannabis plants do not develop flowers, they do not develop calyxes either.

A calyx is a sort of platform made up of tiny leaves called sepals arrayed in a perfect Fibonacci spiral that provides the protection for the forming flower. More specifically, the sepals protect the plant’s reproductive organs, or pistils and trichomes, located between them and provides the overall flower more stability and support for its burgeoning weight.

The benefits of providing physical stability and support to the weight of a cannabis flower may be obvious, but why is it so important to protect the plant’s pistils and trichomes? The answer is that they are instrumental to different aspects of the plant’s growth and development.

Close-up of persons hands holding fresh harvest of hemp plant

Pistils develop the long hairs known as stigmas where pollen from male plants sticks to pollinate the plant and cause it to produce seeds. To get the revered “sinsemilla” cannabis, or cannabis without seeds, no pollen can come in contact with those stigmas.

For cannabis growers, a valuable purpose of pistils is to help identify where the plant is in its blooming cycle and, consequently, how near to harvest. Over time during a cannabis plant’s flowering cycle, these pistils turn from white to yellow to amber or brown, and they go from sticking out straight to curling.

Trichomes are the resin-producing glands of the cannabis plant. These resins are the so-called “oils” responsible for the recreational and therapeutic effects associated with cannabis use.

As the trichomes produce resins, those resins stick to the pistils not unlike pollen otherwise would.

How to identify a swollen calyx vs a pollen sac/hermie plant

Most of the cannabinoids a cannabis plant produces are produced in the calyxes. When the plant has produced its critical mass of resins, these calyxes appear to swell, indicating to experienced growers that it’s time to harvest the plant.

These calyxes, pistils and trichomes collectively form the cannabis flower that is harvested, dried and cured to produce usable cannabis flowers, commonly known as “buds.” If a grower harvests a cannabis plant before these calyxes swell, then those buds will not have all the oils, or potency, that they could’ve had if the grower had given the plant proper time to finish.

Signs of a Swollen Calyx

Swollen calyxes generally look thicker and more solid than they did before they swelled. Signs of a swollen calyx include:

  • It looks like it has seeds but it doesn’t.
  • The flower’s shape takes on a more crystalline structure.
  • Crowning, or small tufts of what look like white pistils sprouting from various tips, may occur.

What is a calyx-to-leaf ratio?

Harvesting a cannabis plant involves trimming off all the leaves in order to expose the flowers, or buds, to then dry and cure. There are two kinds of these leaves:

  • Fan leaves – The large “solar panel” leaves that often turn yellow and fall off on their own sometime during the flowering cycle
  • Sugar leaves – The smaller that stick out of the flowers and are often coated in the same resin, or “sugar,” that coats the buds

While fan leaves are relatively easy to trim, sugar leaves can be a challenge to trim. For one, they are so small that it can be difficult to trim them off without accidentally clipping off some of the bud itself.

For another, the sugar coating them is so sticky as to get on your hands and trimming equipment, making trimming, and cleaning up afterwards, all the more difficult. The calyx-to-leaf ratio relates, specifically, to the proportion of calyxes on a plant to the sugar leaves surrounding them. Fan leaves do not factor at all into this ratio.

The young person sniffing marijuana buds, close-up.

A plant with a high calyx-to-leaf ratio does not have a lot of sugar leaves per calyx and is, therefore, easier to trim. By contrast, a plant with a low calyx-to-leaf ratio has many sugar leaves surrounding each calyx and is, therefore, harder to trim.

Growers will often choose strains of cannabis seeds and seedlings with high calyx-to-leaf ratios in order to limit the amount of trimming they have to do at harvest time to prepare the buds for drying and curing.

Note that sugar leaves can be quite useful. You can use them to produce a host of cannabis derivative products, such as:

  • Topical creams, ointments and lotions
  • Tinctures and extracts
  • Cannabis butter and edibles
  • Hashish

About Hermaphrodite Plants

Hermaphrodite plants are like hermaphrodite animals in that they contain genetic elements, and often reproductive parts, of both the males and females of their species. A hermaphrodite cannabis plant, therefore, is a cannabis plant that presents both male and female reproductive parts.

Typically, this occurs in the form of pollen sacs, or false seed sacs, developing inside the cannabis flowers. This pollen can then release onto the hermaphrodite’s calyxes, sticking to their pistils and causing actual seeds to develop inside the buds.

Close up view of green cannabis leaf and marijuana buds

For a grower and user of cannabis, seeds inside the flowers can be a nuisance. For one, they take up space, and weight, that could otherwise be taken up by resinous trichomes, pistils and calyxes.

For another, they take up energy that the plant could otherwise use to produce more resin. Hermaphrodite cannabis plants, therefore, tend to contain less-usable and lower-potency flowers than purely female cannabis plants.

Causes of Hermaphroditism in Cannabis Plants

The most common reason a female cannabis plant turns into a hermaphrodite is stress. Common causes of stress to cannabis plants that could lead them to become hermaphrodites include:

  • Erratic light schedule
  • Extreme temperatures or humidity
  • Erratic, insufficient or excessive watering or feeding
  • Constant, jarring movement, though they enjoy a light breeze, such as from an oscillating circular fan
  • Harvesting too late
  • Damage, such as broken branches or damaged roots
  • Pruning or staking during the flowering stage
  • Pests and diseases
  • Chemical stress from pesticides and fungicides

In addition, some cannabis strains are simply more genetically inclined to turn hermaphrodite than others. Sativas in general have a higher tendency to become hermaphrodites than indicas.

Signs of a Pollen Sac

When a pollinated cannabis plant begins to grow seeds, they start as pollen sacs. As that pollen sac develops, a calyx grows around it like a sheath to cover and protect it, making it even harder to distinguish a calyx on a female plant from a pollen sac on a hermaphrodite plant.

Fittingly, a pollen sac looks similar to a seed forming with a sheath around it. One way to help distinguish a pollen sac from a calyx is to squeeze it.

Signs of a Pollen Sac

If it feels almost hollow, like a small, blown-up balloon, or liquid squeezes out, it’s likely a pollen sac, whereas a calyx will feel more solid.

How to Prevent Your Cannabis Plants from Becoming Hermaphrodites

While you can’t completely prevent plants from being or becoming hermaphrodites, there are certain measures you can take to reduce the chances of that happening. First and foremost among these is to avoid causing your cannabis plants any sort of stress.

Specific tips for accomplishing this include:

  • Maintain satisfactory growing conditions in your growing space.
  • Keep your growing space clean and sanitized.
  • Make sure your growing space is properly ventilated, with sufficient circulation but no exposure to outside elements like insects.
  • Install a temperature and humidity thermometer and use them to keep the heat and humidity in the room properly regulated.
  • Check your timers regularly to make sure they’re still accurate and operational.
  • Regularly check your plants for mites and other insects as well as mold and mildew, and treat accordingly anytime you spot any.
  • Always pH-balance your water and nutrients before feeding your plants.
  • As harvest approaches, check your calyxes for swelling to make sure you don’t harvest too late.

What should you do if you have hermaphrodite cannabis plants?

If you discover that you have hermaphrodite plants, separate them from your other plants immediately, as the pollen their seed sacs contain can pollinate your other, purely female, plants and cause their flowers to develop seeds.