Daily Light Integral (DLI)

Last Updated: August 13, 2018

Definition - What does Daily Light Integral (DLI) mean?

Daily light integral (DLI) is the number of light particles, also called photons, that are received during a 24-hour time span in one location. Plants require photons for photosynthesis, which is the process of converting light and carbon dioxide into sugar and oxygen so that the plant can survive and grow.

In order for photosynthesis to occur the plant must be exposed to 400 and 700 nanometers (nm) of light. Some plant types require more or less light exposure.

MaximumYield explains Daily Light Integral (DLI)

Daily light integral is the amount of light that reaches one square meter of space, which is 10.8 square feet. This is the light that a plant utilizes for photosynthesis. Typically, the more DLI that a plant is exposed to on a daily basis, the better the plant will grow.

The measurement of DLI is the formula: moles of light (mol) per square meter (m) per day (d), so 1 mole of light is roughly 6×10 photons. Most plants, such as cannabis require an average DLI of 4-6 molam-2ad-1.

Many factors such as plant type, temperature, humidity, and nutrients also have a bearing on how a plant grows and utilizes the available DLI.

Cannabis plants are considered short-day plants, which means they flower when the night exceeds the daylight hours. Despite needing a longer period of dark to spur flowering, cannabis plants also require adequate DLI for growth.

This definition was written in the context of Cannabis
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