Regular light cycles--alternating light and dark conditions--are extremely important to indoor growing. Regular light is important to the growth and development of any plant, according to indoor growing expert Erik Biksa. Not all plants need the same amount of light, and most plants need light cycles that correspond to certain grow cycles inherent to the plant.
Changing Light Cycles
Getting indoor plants to grow well and produce heavily requires light cycles that mesh with the different stages of growth and development of indoor plants. Biksa reports that some plants can withstand 24-hour light while seedlings and during vegetative growth cycles, but that most plants require shorter light times while flowering or fruiting and ripening.
Biksa notes that the majority of plants grown indoors are short-day plants. These plants require decreased day lengths, usually 12-hour light periods, in order to flower. These plants require 12 hours of uninterrupted light and 12 hours of uninterrupted dark if they are expected to produce fruit.
Biksa notes that less common long-day plants require long, up to 18-hour, light cycles and shorter dark cycles to flower. Uninterrupted light cycles are important, as it is possible to interrupt the dark cycle and "trick" a long-day plant into flowering, says Biksa. This may force the plant into premature fruiting and harm yields.
Day-neutral plants are plants that "auto flower"--flower once reaching a certain size or age--and are unresponsive to light cycles; however, Biksa notes that temperature and light spectrum may play a role in how some of these plants flower. Day-neutral plants need light, but it is unnecessary to provide timed light cycles.
Biksa notes, "It is especially important for the indoor grower or greenhouse grower forcing flowering to maintain an uninterrupted dark cycle." Plants need light to photosynthesize, but darkness is just as important to give a plant time to convert photosynthesized nutrients into plant growth.