Plant light meter guide
How to use your phone as a plant light meter
A plant light meter helps you stop guessing whether a window, shelf, or room is bright enough. LumaLeaf uses the phone light sensor to measure lux at the spot where your plant lives, then keeps the reading with the plant profile.
What to measure
Measure at leaf height, with the phone facing the same direction as the plant receives light. Repeat the reading near the same time of day when you compare locations.
How to interpret readings
- Low readings usually mean the plant may need a brighter window, a closer grow light, or a different shelf.
- Very high readings can still stress shade-loving houseplants, especially when direct sun heats the leaves.
- Phone lux readings are useful for home care decisions, not laboratory PPFD or DLI precision.
Why save readings
Plants respond over days and weeks. Saving a reading lets you compare a stressed plant with its previous spot and decide whether light was part of the problem.