Lighting & Spectrum

Crop DLI Analysis

Pick your crop, ZIP code, month, and greenhouse glazing — this estimates the natural DLI reaching your canopy, adds your supplemental light, and shows the gap to the crop's target so you know exactly how much lighting you still need.

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What it does

DLI ("daily light integral") is the total amount of usable light your crop receives in a day, in moles of light per square meter. Every crop has a target DLI it wants; this tool estimates how much of that comes free from the sun through your greenhouse cover at your location and time of year, adds what your grow lights contribute, and shows the shortfall you still need to fill.

When to use it

When planning or sanity-checking supplemental lighting for a greenhouse — especially heading into winter, when natural light drops and the gap to target grows. Enter your crop, ZIP, the month you’re worried about, and your greenhouse glazing to see whether your current light schedule actually hits the crop’s DLI target.

How it calculates

Natural DLI is a clear-sky engineering estimate at your ZIP’s latitude for the 15th of the selected month, cut by the glazing’s PAR transmittance and a typical 75% clear-sky factor — not a substitute for on-site light-sensor data. Overcast regions/months run lower.
ZIPs not in the precise database resolve to a regional centroid by first digit (labeled “approx.”); latitude, not the exact town, drives the estimate.
Crop target DLIs are directional mid-range values; steer to your own agronomic target where you have one.

What you enter

Crop: Choose from: Leafy greens / lettuce (12 mol target), Herbs (basil, etc.) (15 mol target), Strawberry (17 mol target), Cucumber (20 mol target), Tomato (22 mol target), Pepper (22 mol target), Cannabis (vegetative) (25 mol target), Cannabis (flowering) (40 mol target)
ZIP Code
Month: Choose from: January, February, March, April, May, June, July, August, September, October, November, December
Glazing / Cover: Choose from: Open field (no cover) (100% PAR), Single glass (90% PAR), Double glass (82% PAR), Twin-wall polycarbonate (78% PAR), Acrylic sheet (85% PAR), Double-layer poly film (70% PAR), Single-layer poly film (85% PAR), Diffused glass (83% PAR), Shade cloth 30% (70% PAR), Shade cloth 50% (50% PAR), Shade cloth 70% (30% PAR)
Supplement Hours/day
Fixture PPFD (µmol/m²/s)

What you get

Resolved Location
Crop Target DLI (mol/m²/day)
Natural DLI at Canopy (mol/m²/day)
Actual DLI — Natural + Supplement (mol/m²/day)
DLI Gap (mol/m²/day)
Gap (%)
Hours to Hit Target at this PPFD

Reading the result

Natural DLI at Canopy is the free sunlight after your cover; Actual DLI adds your fixtures. If the DLI Gap is 0, you’re meeting the target — anything above 0 is the daily light shortfall. "Hours to Hit Target at this PPFD" tells you how long to run that fixture to close the gap; if it exceeds a sensible photoperiod, you need brighter fixtures or more of them, not just longer hours. Re-run for December vs June to see how much the season swings your supplemental need.

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