Sexing Cannabis: A three-part series from cannabis physiology and physical differences between sexual organs, to tips for sorting genders that works best for your medicinal garden.
PART II: Physical differences between boys and girls
Welcome back to our three-part series on sexing! In our last segment we covered the basics:
- Monoecious / məˈnēSHəs/ = plants that simultaneously express both male (staminate) and female (pistillate) flowers on the same plant
- Dioecious / dīˈēSHəs/= plants that individually express male and female sexes separately on different plants
Cannabis plants are:
- fundamentally either male or female but have the ability to turnhermaphroditic- i.e. female plants can grow male sex organs and produce pollen and likewise male plants can grow female pistils
- producers of Delta 9 Tetrahydrocannabinol (THC)—a pharmacologically-active organic compound with pain-relieving and healing properties
Now, let us move on and dig a little deeper into the physical differences between male and female plants. All dioecious plants experience three growth phases: seedling, vegetative, and flower/bloom. Between the later stages of vegetative growth and the beginning stage of flowering sexual maturity occurs. From a physical standpoint sexual maturity begins at the onset of alternating phyllotaxy, the arrangement of leaves on a stem. Early into vegetative growth petioles (what connects leaves to the main stem) are parallel to each other in respect to the petiole sets on both the nodes above and below. At the onset of sexual maturity, these petiole sets begin to alternate at every node, becoming perpendicular to the leaf set above and below them. Basically, alternating arrangement of leaf sets indicates pre-flowers will begin showing soon! But this begs the question, where will these pre-flowers start popping up?
Ideally 2-3 nodes below the highest node of the plant is a good spot to begin scouting out pre-flowers. You should be looking for pistillate pre-flowers at the node between the stipule (leaf spur) and emerging branch. A macro lens/ jeweler’s loop (your tool of choice really) comes in handy at this point as you need to focus your attention where petiole (leaf stem) and meristem (main stalk) meet.
The two precursors for male and female reproductive organs are illustrated in the graphic below as staminate primordia and pistillate primordia (calyx) respectively. For more awesome cannabis physiology graphics check out Robert Clarke’s book Marijuana Botany.
Let’s first take a look at the boys.
55 days or 7 weeks (rounded down) Phantom Cookie Male:
Male pre-flowers usually begin to show before their female counterparts, around 4-6 weeks into vegetative growth from seed. This is definitely a strain specific topic as most indica or indica/sativa hybrids may reveal pre-flowers prior to actually flowering, while a longer-term sativa would show traces 3-4 weeks into flower. Male pre-flowers resemble ball. More specifically, the shape of a rugby ball blunted at one end as it hangs from a slender stem. As development progresses these “balls” begin to multiply and can be found with more frequency at each internode. As the pre-flowers begin to mature they will transition to a more erect stature and if allowed to reach full maturity the balls will gather into bigger sacs resembling grapes on a vine. Male flowers have five colored petals (yellow, white, or green) approximately 5 millimeters in length which compose the calyx—a calyx whose exterior surface is covered with non-glandular trichomes. Pollen grains are yellowish spheres 25-30 microns in diameter.
Males generally tend to be taller (at any stage of growth) than females (to be able to hover over and shower them with pollen), have fewer leaves near the top, often look thinner, have wider inter-nodal spacing, and usually start flowering more readily than females, taking 7 to 14 days to respond to a change in light cycle.
Now onto the girls!
Pistils showing at day 37 or week 5 (rounded down)
Most strains of female cannabis plants will begin to show pre-flowers within 5-6 weeks from seed. Her beautiful pre-flowers resemble a tulip with 2 hairs-like follicles (pistils: pollen catching appendages) emerging from it that extend considerably once flowering starts. The calyx usually measures between 2-6 millimeters in length. Female pre-flowers tend to sit atop the intersection between petiole and meristem, as opposed to the male’s stick and ball structure that hangs out from similar intersections. Instead of having “flower petals” like males do, females produce 2 long stigmas that range in color from pink to lavender. Mature stigmas are primarily used to collect pollen from the air and internalize it via a delivery system whose final stop ends at the ovaries, where once pollinated ultimately lead to seed formation.
In general females are shorter, bushier, have more branches, have smaller distances between inter-nodal spacing, and are symmetrical in overall structure. Female plants tend to be leafier at the top with noticeably more leaves surrounding the flowers. They usually take 7 to 21 days to change from veg to flower when exposed to a 12:12 flowering light cycle.
Letting nature take its course and waiting on the plants to fully develop sex organs requires patience because it can take a considerable amount of time– which is why different methods have been adapted in the cultivating community to help farmers sex plants quicker. Interested in exploring these methods? Check back with us for Part III:Tips for sorting through genders: which method works best for your medicinal garden where we’ll discuss different techniques such as cloning and rooting, manipulating light cycles, and using blue light to help reveal your plants’ sex faster.