Average daily light integral (DLI) from sunlight for any location, by month, with the supplemental lighting a greenhouse needs to reach a crop's target. Search a location or select one on the globe. For fixture sizing, use the Grow Light Planner.
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Sunlight: NASA POWER, all-sky surface PAR (CERES SYN1deg), monthly averages 2001 to 2025. Imagery: NASA Blue Marble. Borders: Natural Earth. All sources
Location
Source: NASA POWER, 1° grid cell (about 70 to 110 km), clouds included. Averages, so a single week can run well above or below.
Greenhouse
Select a growing setup to see the light at the plants and the grow light needed to reach the target.
Averages hide cloudy weeks: a dull stretch can run well under these numbers. Measure at plant height with a PAR meter before buying lights. To size the fixtures, take the PPFD here to the Grow Light Planner.
Related Tools
Size and space fixtures and check PPFD and DLI against your crop's targets.
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Open the chartHeat this season against the average year, for harvest timing, bloom and pest scouting.
Count degree daysWhen to start seeds indoors and when to transplant, from your frost dates.
Plan your seedsDaily light integral is the total light plants can use (400 to 700 nm) that lands on a square meter in a day, in mol/m²/day. Growth follows this daily total more than the brightness at any one moment.
The average for each month over 2001 to 2025, clouds included. Each colored square is about 1 degree across (70 to 110 km), so a valley, a coast or a mountainside can differ from its square. A single week can run far above or below the average.
Glazing, frames and dirt cut the light that reaches the bench. A typical greenhouse passes 50 to 70% of outdoor light (Bizon estimate, 60% used here). If your house runs brighter or darker, enter its figure under Custom. The grow light PPFD is what it takes to close the gap to the low end of the target, run for the hours you enter, on top of the sun.
More on each source on the sources page.