Identifying the sex of a marijuana plant is a primary step for any cultivator aiming to produce consumable flower. Only the female cannabis plant develops the resin-rich buds desired for their cannabinoid content. Male plants produce pollen, and their presence will fertilize females, causing them to divert energy from flower production to seed creation. Early sex identification is critical to ensuring a high-quality, seedless harvest and protecting the yield potential of the crop.
When Plants Show Their Sex
Cannabis plants begin to reveal their sex during pre-flowering, which typically occurs several weeks into the vegetative growth cycle. This phase starts when the plant is mature enough to form its reproductive organs. For plants grown from seed, these initial sex indicators usually become visible around four to eight weeks after germination. Male plants often exhibit these pre-flowers slightly earlier than females, sometimes as early as three weeks. Pre-flowers develop exclusively at the nodes, the points on the main stem where leaf branches extend outward. Cultivators must inspect these junctures carefully to spot the tiny, immature structures.
Visual Identification of Male and Female Pre-flowers
The structures appearing at the nodes provide the clearest visual distinction between male and female plants. Female pre-flowers initially manifest as a small, tear-drop or pointed structure known as a calyx. This calyx is the protective casing for the developing ovule and will eventually become part of the mature bud structure.
The definitive sign of a female plant is the emergence of fine, white, hair-like strands from the tip of the calyx. These strands are the pistils, or stigmas, designed to capture wind-carried pollen. If these hairs are present, the plant is female and should be retained for flower production.
In contrast, the male pre-flower presents as a small, smooth, ball-like sac that forms at the node. These structures are immature pollen sacs, which are clustered together and lack any protruding white pistils. Their visual appearance is often described as resembling tiny grapes or a cluster of miniature green bananas. They rapidly increase in size and number as the plant matures.
Any plant identified as male must be removed from the garden immediately upon discovery. The pollen sacs will eventually ripen and burst open, releasing pollen that can travel long distances on air currents to fertilize female plants. Immediate culling of males is necessary to preserve the quality of the surrounding female crop.
Dealing with Intersex Plants
Occasionally, a cannabis plant will develop both male pollen sacs and female pistils on the same individual; this condition is known as hermaphroditism. These intersex plants can self-pollinate and have the capacity to seed an entire crop, posing a risk similar to that of a purely male plant. Hermaphroditism can be caused by genetic instability within the strain or, more commonly, by environmental stress experienced during the growth cycle.
Stressors such as light leaks during the dark period, extreme temperature fluctuations, or nutrient deficiencies can trigger a plant to express both sexes. The plant attempts to ensure reproduction by pollinating itself when it perceives its environment is detrimental. Growers should vigilantly inspect plants for the simultaneous presence of round pollen sacs and white pistils, especially when environmental conditions have been less than optimal.
Immediate removal of an intersex plant is necessary to protect the rest of the garden from accidental pollination. If hermaphroditism is discovered late in the flowering cycle, one might carefully remove only the male pollen sacs, often referred to as “nanners,” to try and salvage the flower. However, the most reliable course of action is to isolate or remove the plant entirely to prevent pollen spread and the loss of a seedless harvest.