Daily Light Integral (DLI)

Last updated: May 13, 2021

What Does Daily Light Integral (DLI) Mean?

Daily Light Integral (DLI) is the amount of photons (light particles) received by a particular area (1m2) in one day.

DLI greatly affects plant growth and development. In order for photosynthesis to occur the plant must be exposed to 400 - 700 nanometers (nm) of light. Although many plants benefit from controlled DLI, specific levels needed will vary from plant to plant.

DLI can be measured, and its measurement is particularly important to commercial farmers and growers that use greenhouses.


Maximum Yield Explains Daily Light Integral (DLI)

Knowing an area’s particular Daily Light Integral can help farmers and gardeners in several different ways. First, measuring an area’s DLI can help a grower decide which crop variety would grow and thrive best a particular location. Additionally, DLI can help growers optimize use of supplemental lighting.

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

To measure DLI, growers will need to purchase a light sensor and record light levels throughout the day. Light sensors and DLI meters can be purchased from specialty stores.

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.

(To learn more, check out The Daily Light Integral Chart: Understanding Your Plants' PPFD & Photoperiod Requirements)


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