by Jorge Cervantes
Flowering
Cannabis is an annual plant that normally produces seeds to successfully complete its life cycle. Marijuana is a dioecious plant, being either male (pollen-producing) or female (ovule and seed-producing). However, intersesx (aka hermaphrodite) plants with both male and female flowers can also occur.
In nature, cannabis flowers in the fall, after long days of summer. The long nights and short days of autumn signal marijuana to start flowering. Plants are normally either male or female.
Growth patterns and chemistry change during flowering: stems elongate; leaves grow progressively fewer blades; cannabinoid production slows at first, then accelerates; and flower formation is rapid at first, then slows. Nutrient needs change as growth stages change. Plants focus on flower production rather than vegetative growth. green leafy growth, requiring nitrogen, slows. Phosphorous and potassium uptake increase to promote floral formation. Shortly before the flowering stage, growers change to a “super bloom” fertilizer formula with less nitrogen and more potassium and phosphorus. Always flush or leach soil with water two or three days before changing to the flowering fertilizer.
When flowers are full of ripe, mature seeds, the female will die, having successfully completed her life cycle. The male completes his life cycle and dies after producing and dispersing all his pollen into the wind, in search of receptive female pistils.
Induce flowering indoors by giving plants more hours of total darkness and fewer hours of light. Give cannabis 12 hours of uninterrupted darkness and 12 hours of light to induce visible signs of flowering in two weeks or less. This program is effective in all but the latest-blooming pure sativa strains.
Often, when using low-nitrogen, high-phosphorous and potassium bloom formulas, large older leaves yellow or turn purple during flowering. Such fertilizers make buds swell with resinous growth.
Water intake of flowering plants is usually somewhat less than during the vegetative stage. Adequate water during flowering is important for plants to carry on internal chemistry and resin production. Withholding water to “stress” a plant will actually stunt growth and diminish yield.
Inducing flowering in cannabis grown from seed with a 12/12 day/night photoperiod will cause plants to show sex, male or female. Once the sex of the plant is guaranteed, males are almost always harvested before they shed pollen, and females are coaxed into higher yields. Once the photoperiod is set, disrupting it will cause plants to suffer stress. If they suffer enough stress, hermaphrodite tendencies increase.