Male vs Female Weed Plants

Understanding the difference between male and female weed plants is crucial for any cannabis grower. Knowledge of a plant’s anatomy gives growers a visual tool to evaluate a plant’s growth in the garden and set it up for success.

Environmental cues such as the amount of daylight, temperature, and humidity can all trigger a plant to transition from the vegetative stage of growth to reproductive or flower stage of growth. When this happens, growers need to know what they’re looking at to help prevent unwanted pollen from being spread in the garden or to pinpoint when a plant isn’t maturing as it should be.

Female weed plant

As female plants develop and begin their reproductive growth, they produce promorida, which form at the nodes of the plant. These primordia turn into calyxes from which white, hair-like structures emerge. These white hairs are part of the reproductive organs in the female plant and form the pistil, which consists of the ovary, style, and stigma. Because only the fused style and stigma protrude from the calyx as a white hair-like structure, the cannabis community refers to the white hairs as pistils.

Two cannabis calyx examples.

As the plant continues to flower, more calyxes form, stacking on top of one another to form the large colas we all know and love. As calyxes continue to grow and swell, they become encased in a layer of trichomes that protect the plant’s reproductive organs from the environment. The trichomes are filled with all the wonderful compounds the cannabis plant can produce. 

Male weed plant

The first new reproductive growth of a male cannabis plant starts with the growth of primordia at the plant nodes. The primordia will mature into a staminate calyx, which is referred to as a pollen sac among cannabis growers. Within the staminate calyx, the stamen and the anther are formed. The anther sac contains the pollen that will germinate a female calyx, and the stamen is a pedal structure that emerges from the staminate calyx. 

Male cannabis plants

As the calyxes mature, they open up and blossom to release the pollen from the anther into the atmosphere. Male cannabis plants mature much faster than female cannabis plants, typically finishing within four to six weeks after the first signs of reproductive growth. 

How to tell male vs female weed plants

Male cannabis plant signs

• Thick stems
• Few leaves
• Hardly resinous
• Pollen sacs at nodes 

Female cannabis plant signs

• Thin stems
• Many leaves
• Very resinous
• Pistils on flowers

Hermaphrodite weed plant

A hermaphrodite cannabis plant contains both female and male reproductive parts. Typically, this equates to seeds being produced in buds. When a female plant is under stress, it has a greater likelihood of turning into a hermaphrodite. This stress can be from too much light, prolonged high temperatures, underwatering, overfeeding, pressure from pests, or even letting a plant mature for too long. 

The goal of a cannabis plant is to reproduce, so when we let plants mature for too long, they can start to produce male sexual organs to help reproduce. Besides stress, genetics can play a major role in hermaphroditism, with some genotypes being more susceptible to growing both male and female flowers even if the plant isn’t under stress. Growers need to make sure they are getting their genetics from vetted sources that have proven track records of producing winning female plants. 

How to tell a female cannabis plant from a male

1. To determine the sex, start looking for signs of male and female cannabis pre-flowers, or primordia, forming at the nodes of the plant. This typically starts in mid-July when growing in the summer season outdoors, and after one week of switching to a 12/12 light cycle when growing indoors. A female plant shows tighter internode lengths and will usually have more leaf sets, compared to males that will traditionally have thicker stems and grow taller.
2. After two weeks of flowering growth, primordia will begin to differentiate between male and female plants. Male preflowers’ primordia will form into a claw-like shape, and female preflowers’ primordia will form into a pod-like shape with pistils of white hairs protruding from them.
3. After four weeks of flowering, female plants will begin producing leaves with fewer leaflets per leaf, and calyxes will begin to swell as the reproductive organs are formed inside. Trichome production is also increased to help protect the sexual organs of the plant. Male plants will have mature staminate calyxes at this stage of flower, with some opening up and releasing their pollen. Any male plants should be removed from the garden before the staminate flowers open and their pollen is released, unless you are trying to grow seeds in your garden!
4. At weeks six to seven of flower, female plants will have almost stopped producing leaves and are solely focused on calyx formation and trichome production. The white hairs will start turning orange at this point, and the plant is beginning to finish up its light cycle. Male plants will be finishing up their lifecycle at this point, staminate flowers will have fully matured, and will have released all of the pollen they produced. 
5. Depending on the variety, female cannabis plants will continue to stack and swell with calyx building until maturity is reached and trichomes begin degrading. A typical female flowering plant will grow eight to nine weeks, but some varieties can take over 12 weeks to mature. 

How to identify a female seed

When you get a seed, the only way to truly know if it is a female is to send it to a lab for genetic testing. Otherwise, you have to trust the breeder that you purchased seeds from to produce high-quality feminized cannabis seeds. To achieve feminized seeds, breeders use a technique that allows a female plant to pollinate itself, which creates only one combination for genetics. 

This process produces seeds that are 99.99 percent female, but there is always a chance that a male could pop or a plant could turn out to be a hermaphrodite. A grower needs to be able to identify the male and female parts of the cannabis plants so they understand how a plant looks as it matures, and they can identify any irregular growth that may signal a plant has turned into a hermaphrodite.

Male vs female cannabis plants: an important distinction

Male cannabis generally flower faster than female plants, so it is important to keep a vigilant eye in the garden and monitor new growth as plants move from vegetative growth to flower growth. As the plants begin to express themselves through the formation of primordia into their respective calyces, growers need to be aware of what’s next in the plant’s life cycle and plan their garden accordingly. Male marijuana plants should be identified as early as possible to ensure they can’t pollinate the females unless, of course, your goal is to grow seeds instead of cannabinoids and terpenes.