Under artificial light the photoperiod is, of course, any length you wish. The most popular way to grow with artificial lights is the harvest system. Start the plants under long light periods of from 16 to 18 hours daily. After the plants have reached a good size, usually between three and six months, shorten the light cycle to about 12 hours to force flowering.
To decide exactly when to grow cannabis and force the plants to flower, let their growth be the determinant. If male plants are showing their flowers, then the females are physiologically ready to flower. Most of the plant's overall height is achieved during vegetative growth. Some varieties, of course, are smaller and grow more slowly than others. Wait until the plants are nearing the limits of the height of the garden or are at least five feet tall. This is large enough to support good flower development and return a good yield. If you turn down the light cycle when the plants are young and small, you'll harvest much less grass because the plants simply can't sustain a large number of flowers. Some leaf growers prefer a continuous growth system, emphasizing leaf growth and a continuous supply of grass. The light cycle is set for 18 to 24 hours a day. This prevents flowering and the plants continue their rapid vegetative growth. Growing shoots and leaves are harvested as used, and plants are removed whenever they lose their vigor and growth has noticeably slowed. New plants are started in their place. In this way, there will be plants at different growth stages, some of which will be in their rapid vegetative growth stage and will be quite potent. Male plants and some females eventually will form flowers,but the females will not form large clusters. People often use this system when the lights are permanently fixed. Small plants are raised up to the lights on tables or boxes. This garden never shuts down and yields a continuous supply of grass.
