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 Seventeen, "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 to stop high THC production and start seed formation. Remove and destroy males, except those used for breeding, as soon as their sex has been determined. The instant they show sex, separate male plants used for breeding from females. Do not let them shed pollen. Premature pollen sacks often form and open early or are hidden under foliage and go unnoticed until it is too late. If growing from seed, take special care to ferret out male flowers and plants.

Growers have reported that bouncing the photoperiod around and dynamically raising or lowering the temperature have the effect of producing more male plants. Note that each stimulus involves creating a climate that causes plants to suffer stress. Also, the stressful environment does not necessarily turn the entire plant male; it turns it hermaphrodite. The most susceptible plants already have a predisposition to hermaphrodism. See Chapter Sixteen, "Breeding," for more information.

The red arrow shows where pre-flowers develop on both male and female flowers.

There are several ways to promote male or female plants during seedling growth. (See "Grow More Female Plants from Seed" in Chapter Two). During vegetative growth you can get a good idea of a plant's sex from its genetic background and growth characteristics. The most dependable way to deduce sex is "Cloning for Sex" (see Chapter Three). For a complete discussion, see Chapter Sixteen, "Breeding."

Female Pre-flowering

Near the end of normal vegetative growth, plants grown from seed develop pre-flowers. This is when female calyx formation initiates, and it is not contingent upon photoperiod. It occurs when a plant is old enough to show signs of sexual maturity, about the fourth week of vegetative growth, or six to eight weeks from germination. The pre-flowers emerge behind the stipule at the fourth to fifth branch internodes.

A pre-flower looks like a regular female flower; most have a pair of white fuzzy pistils. Pistils normally form after the light green seed bract part of the pre-flower has formed. Wait until pistils have formed to ensure the plant is a female and not a male. The preflowering stage lasts from one to two weeks. A little patience is in order now!

Plants grown from seed under an 18/6 day/night photoperiod will usually show pronounced pre-flowers before plants given a 24/0 day/night photoperiod. And, under a 16/8 day/night regimen pre-flowers show more quickly and are often more pronounced. Once pre-flowers are distinguishable as male or female, plants can be induced to flower with a 12/12 day/night photoperiod.

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 odd growth, and plants might grow into hermaphrodites. Inducing flowering before preflowers form will not speed flowering. Flowering will occur about the same time as if you had waited for pre-flowers to show!

The green calyx supports two very small pistils on this pre-flowering 'Flo' from DJ Short.

The pre-flower on this 'Mr. Bubble' female is very easy to spot with the naked eye.

Pre-flowers on this 'Puna Budder' from THSeeds are nearing the end of the pre-flowering stage that lasts about two weeks.

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