Biotic Instruments
Know exactly how much light a spot gets — and whether the plant you want will grow there. Free for iPhone.
Free
Price
3
Units — fc · PPFD · DLI
12 months
Seasonal forecast
Any iPhone
No LiDAR required
Why the Plant Light Meter
Readings come from the camera's own exposure data — not a guess from screen brightness. You get a number you can compare from spot to spot and day to day.
Choose a plant and the app tells you whether the spot suits it. When it doesn't, it suggests plants that would do well in the light you actually have.
Scan a room and see daylight modeled across the entire floor at plant height — through the room's real windows, at your real latitude.
Light changes through the year. The app forecasts month-by-month DLI for any spot, so you can place a plant for the whole year, not just for today.
LiDAR makes the room scan faster on Pro models, but it isn't required — tap the floor corners in AR and any recent iPhone builds the same map.
The readings are estimates for comparing places, not laboratory measurements. The app says so plainly — a tool you can trust is worth more than a number that only looks precise.
Plant Finder
Point at a spot, then check the plant you have in mind. The app ranks your whole library by how well each one suits the light you measured — and tells you plainly when something won't be happy.
Room Light Map
Scan a room — with LiDAR or by tapping the floor corners in AR — and the app models daylight across the floor through the room's real windows. Drop plants onto the map to see how each would fare where you put it.
Seasonal Forecast
Light rises and falls through the seasons. The app forecasts DLI month by month for any spot, so a plant can be placed for how the light will be in December, not just how it is today.
How it works
Aim your iPhone at a wall, a leaf, or the spot you're considering.
The camera's exposure becomes foot-candles, PPFD, and a daily light integral.
Pick the plant you have in mind and see whether the spot gives it enough light.
Scan the space — with LiDAR or by tapping the floor corners — to model daylight across the floor.
Drop plants onto the map and see how each one would fare where you put it.
Switch to the seasonal view to watch light rise and fall month by month, and place for the long run.
The Science
A camera already measures light precisely — it has to, to expose a photo correctly. The Plant Light Meter reads that exposure metadata — aperture, shutter, and ISO — and converts it into illuminance, then into the units plants are grown by: foot-candles, PPFD, and DLI.
Every iPhone's sensor and lens differ, so each model is calibrated against a reference meter. A reading on one phone means the same as a reading on another.
These are estimates, built for comparing one spot to another and one month to the next — not lab-grade measurements. The app says so, and so do we: the value is in the comparison, and the comparison is reliable.
When a spot falls short
Sometimes a spot simply doesn't get enough light for the plant you want, and no placement fixes it. That's the problem Biotic Instruments builds hardware to solve. The Green Divider brings its own full-spectrum grow lighting, and our controllers add supplemental light wherever daylight runs short — so the plant you want can live where you want it.
Free on the App Store
Requires iPhone, iOS 15 or later