A light cycle, in the context of cannabis cultivation, refers to the specific timing and duration of light and dark periods provided to plants during the vegetative and flowering stages. Light cycles are manipulated to mimic natural lighting conditions and trigger specific physiological responses in cannabis plants, such as vegetative growth and flowering.

For indoor cannabis cultivation, growers have control over the light cycle by using artificial lighting systems, such as high-intensity discharge (HID) lamps, fluorescent lights, or light-emitting diodes (LEDs). The most common light cycles used are:

1. Vegetative Light Cycle: During the vegetative stage, cannabis plants require longer light periods to promote vigorous vegetative growth, including the development of leaves, branches, and roots. The most common vegetative light cycle is 18 hours of light followed by 6 hours of uninterrupted darkness (18/6). Some growers may also use a 24-hour continuous light cycle (24/0), but this is less common as plants benefit from a period of darkness for proper rest and metabolic processes.
2. Flowering Light Cycle: To initiate and maintain the flowering stage, cannabis plants require a change in the light cycle, specifically a reduction in the amount of light and an increase in the uninterrupted dark period. The most commonly used flowering light cycle is 12 hours of light followed by 12 hours of uninterrupted darkness (12/12). This light cycle mimics the shorter days of late summer or early fall, triggering the plant’s transition to the reproductive stage and the development of flowers.

It’s important to note that different cannabis cultivars may have specific light cycle requirements, particularly those classified as “photoperiod” strains. These strains require a change in the light cycle to initiate flowering, while “autoflowering” strains will transition to flowering automatically based on their age, regardless of the light cycle.

Maintaining consistent and precise light cycles is crucial for cannabis growers as any disruptions or deviations can impact the plant’s growth, development, and flowering. Light cycle interruptions during the dark period, even brief exposure to light, can interfere with the flowering process and result in irregular growth patterns or reduced yields.

Additionally, it is essential to provide the appropriate intensity and spectrum of light during each stage of the plant’s life cycle. This ensures optimal photosynthesis, energy absorption, and overall health. LED grow lights have gained popularity in cannabis cultivation due to their energy efficiency and the ability to provide customizable light spectra tailored to the specific needs of plants during different growth stages.