What is Daily Light Integral (DLI)?

Views : 87
Update time : 2022-11-17 10:42:31
Daily light integral (DLI) refers to the number of photosynthetically active photons (individual particles of light in the 400-700 nm range) that are delivered to a specific area over a 24-hour period. In other words, it is the amount of light intensity the plant receives each day.

The equation for converting Photosynthetic Photon Flux Density (PPFD) to DLI, assuming constant PPFD, is below.

DLI (mol/m²/d) = PPFD*Light-hours/day* 3600s

  • Light-hours is the number of hours in a day active photons are delivered to the target area, measured in hours.
  • 3600s is one hour being converted to seconds.

For example, the PPFD that a cannabis plant needs is 600μmol/m²/s. If the plant can get a total 15 hours of lighting a day, then the DLI is 600μmol/m²/s*15h*3600s=32400000μmol/m²/d=32.40mol/m²/d.

If the plant needs a total 1000mol DLI throughout its growing stages and we give it 10mol each day, then it will get 100 days to harvest. But if we give it more mol, it will grow faster and can be harvested in a shorter time.

However, it is far more complicated due to the changeable weather and seasons. So, it is very essential to make reasonable supplemental lighting plans according to the species that you grow in different seasons.
Figure A is the DLI in December in the United States. It is 3mol per day on cloudy days and 9mol per day on sunny days. For most species, this DLI is not enough to reach their fastest growth, so it is necessary to use LED grow lights to fill up the gaps.

Figure B is the DLI of the US in June. The DLI is 12mol per day on cloudy days and that is enough. Of course, it is OK to provide supplementing light. On sunny days, it is 26mol per day, which is great for plants that prefer much light, but some plants that can't be placed directly under the light will need shading.
Above is the monthly DLI of the United States
Related News
Overwatering and Its Solutions Overwatering and Its Solutions
Mar .21.2023
Water is essential for any plant, including cannabis. Without a stable supply of high-quality water, crops can never truly thrive and reach their full potential...
Shark-XR Series for Greenhouses or Other Indoor Projects Shark-XR Series for Greenhouses or Other Indoor Projects
Mar .16.2023
Are you looking for a reliable and affordable solution for greenhouses or other indoor projects? Look no further than the Shark-XR series...
How to Transplant Cannabis Plants? How to Transplant Cannabis Plants?
Mar .14.2023
The term "plant combination" usually describes a method of asexual reproduction (reproduction without the transfer of fertilized eggs or genetic seeds from one organism to another, such as grafting)...
What Should Be Considered to Start An Indoor Cannabis Grow What Should Be Considered to Start An Indoor Cannabis Grow
Mar .09.2023
With more states adopting cannabis legalization laws each year, the cannabis industry is continuing to grow...