A PRACTICAL STARTING POINT
Match the light.
Choose a plant.
Enter a reading taken where the leaves will be. The result compares it with broad extension-education ranges and offers a short list of plants commonly associated with that range.
YOUR WINDOWSILL / 01
What does the spot measure?
Use the phone or meter at leaf height, facing the same direction as the leaves. Repeat at different times; one reading is only a snapshot.
BROAD LIGHT BAND
Medium-bright light
Plants listed in this broad range
These are starting points, not a guarantee of growth or a precise species-level prescription. Cultivar, light quality and duration, season, temperature, water, and acclimation all matter. Check your plant’s care label and observe its growth.
READINGS ARE CONTEXT
Lux is not plant-usable light.
Lux and foot-candles describe brightness weighted for human vision. They do not measure plant-useful wavelengths the way PPFD does. This tool uses broad foot-candle categories as a practical comparison only.
Phone light-meter apps vary by device and calibration. Use one to compare places on the same phone; use a calibrated meter for a more dependable illuminance reading. Neither reading by itself captures daily light duration or spectrum.
Sources and method
- University of Maryland Extension: Lighting for Indoor Plants — categories and example species.
- University of Minnesota Extension: Lighting for Indoor Plants — intensity, duration, light quality, and supplemental lighting.
- University of Illinois Extension: Lighting — differing practical category thresholds and seasonal context.
The ranges vary among extension sources; the tool follows the broad categories in the University of Maryland chart and labels the output accordingly. It does not infer an exact daily light integral (DLI).