Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

is the point of sexual maturity, the first sign a plant is preparing for flowering–the next stage in life.
    You can see pre-flowers with the naked eye, but a 10 to 30X magnifier will make viewing easier. You can accurately determine plant sex after eight weeks. Using this method, you can distinguish sex before inducing flowering.

Early male flowers are easy to spot with the naked eye. They are located at branch internodes.
Male Pre-flowering
    Male pre-flowers are normally visible when plants are six to eight weeks old, after the fourth week of vegetative growth. The pre-flowers emerge behind the stipule at the fourth to fifth branch internodes and generally do not turn into full flowers. But, according to Bongaloid www.overgrow.com , now shut down) “a male plant will develop mature staminate flowers after prolonged periods of vegetative growth.”
    Always wait to induce flowering until after pre-flowers appear. Inducing flowering with 12 hours of uninterrupted darkness and 12 hours of light before pre-flowers develop will stress the plant. This stress could cause peculiar growth, and plants might develop into hermaphrodites. Inducing flowering before pre-flowers form will not expedite flowering. In fact, flowering will occur at about the same time as if you had waited for pre-flowers to show!

Male pollen sacks hang like little balls. Each pollen sac has enough pollen to pollinate all the females in the average grow room.

Male flowers develop quickly on the tip of this male plant. Keep an eye out for male plants, and separate them from females as soon as they are spotted.

This male plant is in full bloom. Flowers open over the course of a week or longer to ensure females are completely pollinated.
    Plants grown from seed under a 24/0 photoperiod will generally show pre-flowers after plants that are given a 18/6 day/night photoperiod. Once pre-flowers are distinguishable as male or female, plants can be induced to flower with a 12/12 day/night photoperiod.
    A word of caution from bc-trichome-farmer (the extinct site, www.overgrow.com ): “Do not try to sex a seedling based on the very first pre-flower. Wait and make sure. The time between using a 25X (loupe) to spot the very first pre-flower and the plant dropping pollen is at least 10+ days away, so it’s safe.”

This beautiful male flower has dispersed its yellowish pollen into the air.

Grains of pollen are miniscule. This close-up of a grain of male pollen is magnified 4000 times. Cannabis cohort Eirik captured this image on a scanning electron microscope.

Male Flowering
    When given a 12/12 day/night photoperiod, male cannabis reaches maturity and flowers one to two weeks before females. However, male plants do not necessarily need a 12/12 day/night photoperiod to dawn flowers and shed pollen. Males can flower under long days and short nights as well, but they generally produce fewer flowers. Once male calyxes show, pollen develops quickly and can disperse within a very short time. There is always an early opener that sheds pollen, often within 24 hours or less! To avoid pollination problems, remove males as soon as they are distinguished. If growing male plants, always isolate them from females, so they will not be pollinated. See Chapter 5, “Harvest,” for more information on harvesting males.
    Males continue flowering and shedding yellowish, dust-like pollen from bell-shaped pollen sacks well into the females’ flowering stage, which ensures pollination. If you are making seeds, pollinating females too early, before the girls have developed many receptive female pistils, will result in a small seed crop. See Chapter Sixteen, “Breeding,” for more information.
    Male flowers are about one quarter-inch (6 mm) long and pastel green to yellowish in color. Flowers first develop near the top of the plant. Pollen sacks develop on a short spike and hang in clusters at the base of branches. Gradually, flowers develop towards the bottom of the plant. After two to six weeks of the 12-hour photoperiod, fully formed floral sacks split open and shed pollen.
    Males are usually taller than females and have stout stems, sporadic branching, and fewer leaves. In nature, wind and gravity carry pollen from taller males to fertilize (pollinate) receptive females. Male plants produce fewer flowers than females, because one male plant can pollinate many females. Males also contain less THC and overall lower cannabinoid levels.
    Males fertilize females, causing them