The goal of the closet cultivator is to grow plants which yield a large crop of sinsemilla, the unfertilized female flowers of the plant. Usually male and female flowers grow on separate plants. By removing the male plants from the garden, the females remain unpollinated. Pollinated plants put much of their energy into producing seeds, rather than bud growth.
Unpollinated plants grow clusters of flowers over a period of 4 to 8 weeks. Within a few weeks the growth takes the shape of a bud. As the buds ripen, the clusters of flowers grow thicker and the resin glands found on the small leaves and branches begin to swell as they fill up with THC. When it is ripe, the bush fluoresces with 10,000 points of light.
When to Flower
Indoors, growers force marijuana to flower at any time. Even seedlings will indicate sex and produce flowers given the right conditions.
Marijuana flowers in response to the light cycle. Under natural conditions, the plant senses oncoming autumn by chemically measuring the uninterrupted dark period. Indoors, when the light regimen includes a dark period of 10-12 hours each day, the plant stops its vegetative growth cycle and starts growing reproductive organs, male and female flowers, which usually occur on separate plants.
When light hits a leaf the tissue absorbs certain rays which it uses in photosynthesis. Those rays are unavailable to leaves below the top. 1000 watt HID lights penetrate only 12-18 inches of leaves depending on their size and quantity. Vegetative material below this canopy receives little light, does little photosynthesizing and produces little energy for the plant.
Since a tall plant produces no more than a short one, the plants are forced to flower when they are 8-15 inches tall. At maturity they will stand only 18-36 inches.
When the light cycle is switched to "short day," the plant's growth changes from vegetative - the production of leaves and stems, to the reproductive cycle. A few days after the change in the light regimen, all visible growth slows down. Then the first flowers appear.
Males usually indicate first. Using a photographer’s loupe or a magnifying glass, the immature male flowers can be differentiated from the females. They look like small pawnbrokers balls hanging from a stem, or a small cluster of grapes. The mature flowers have 5 very small white or yellow petals and a lot of pollen.
The immature female flowers are oval, pointed up and have avery thin hair-like strand extending from each flower. These strands are called pistils and when they pick up pollen which is floating in the air, the flower is pollinated.
As soon as any male plants indicate sex, before the flowers open, growers remove them from the garden. This prevents the females from being fertilized.
Here are the stages of flower growth.
- Slowdown then stop of vegetative growth. 4-10 days after beginning forcing. Lasts up to a week.
- Appearance of first flowers. 10 days to 15 days after beginning forcing.
- Massive growth of flowers at the budding sites. Continuing after the first appearance of flowers for 30 to 40 days. During this time the buds develop and take shape. Starting with a few flowers, layer after layer of flowers is grown until the bud sites are merged together into one large cola.
- Maturation. Eventually the pistils start to turn color from pale white to red or brown At the same time the flowers close up, forming false seed pods. The small glands on the flowers now start to grow. These are called stalked capitate glands and are composed of a tiny stalk supporting a thin clear membrane. As THC is produced near the site, the membrane swells with the potent liquid. The membrane stretches and the gland takes on the appearance of a mushroom. When the glands have swelled and the pistil has receded into the false pod, the bud is ready to pick.
The number of days from onset of flowering to maturity varies depending on variety and the length of the dark period. The shorter the dark period, the faster the flowers mature. However, when the flowers are brought to maturity faster, they are smaller than when they are given more time to mature. For instance, a bud under a regimen of 12 hours of darkness may take 6 weeks to mature. The same bud, kept under a 14 hour darkness regimen may take only five weeks to mature but may weigh 15% less than the longer maturing bud.
Some growers start the flowering cycle at 10-12 hours of darkness. After 4 weeks they turn up the dark part of the cycle to 14-16 hours of darkness and the buds quickly mature.
Sometimes parts of the bud are mature but new growth is continuing. Most growers pick when the rate of this growth slows. However, the mature parts of the bud can be removed using a small pair of scissors. Some varieties respond to pruning by continuing to produce new growth.
A few varieties including Thai and other South East Asian plants are natural hermaphrodites which produce flowers intermittently under a 12 hour regimen. They have adapted to the latitude in Thailand which is close to the Equator and does not have much seasonal variation of daylight hours. Colombian varieties have also adapted to low latitude conditions by prolonging flowering a bit, until it catches up with a chronological schedule.