iPhone Screenshots


Setting up your plants' optimal lighting is not easy — if not impossible without a proper PPFD plant light meter. Calculating your indoor garden's daily light integral (DLI) to match your plants’ needs allows you to optimize your lighting for maximal yield and minimal electricity consumption.

Korona is the world's most advanced plant light meter you always have in your pocket to help you make the right decisions about your plants' lighting conditions.

Korona works by using your iPhone’s front-facing camera and advanced image processing algorithms to sense the light as your plant sees it.

Maximize yield, minimize energy bills.

What’s New

Version 1.1.8

We have introduced some new features and improvements. Korona now runs smoothly on devices running iOS versions lower than 13. The image freezes now when holding, so you can see what kind of image was processed during the hold.

Ratings and Reviews

4.4 out of 5
29 Ratings

29 Ratings

vitvorg ,

Useful and user friendly with a very involved attentive developer!

Best app on the AppStore to estimate PPFD for growing plants. I’m a botanist, and so I know this app won’t replace a $400 par meter, but for quick estimations with your phone? This app is more than worth it. The hold feature is super useful. The background shows a grainy picture that gives you instant feedback that you are aiming your phone correctly, which is a unique feature that even the expensive PAR meters do not have. A suggestion to the developer for a future update would be for the background preview picture to freeze when the hold option is used. The hold option right now freezes the reading which is useful for measuring at actual leaf locations and orientations, but the background picture does not freeze with the reading. It would be amazing for the background image to freeze with the hold measurement, so when you pull your phone back you could see that you were aiming the phone correctly and you could see what you were aiming at when the hold measurement was taken.

Developer Response ,

Thank you very much for your kind and useful review! We will definitely consider the background image hold for a future release!

divergio ,

The best plant light meter I've used.

This app has a nice visualization that helps you aim the camera precisely at the light source. I tried a bunch of others and they mostly failed at this core functionality.

I sought out an app like this after reading “New Plant Parent” and I’ve gotta say it’s really changed my intuitions around lighting. You can use it to see how rapidly the light drops off with distance. I've readjusted all my grow lamps after using it.

Anyway, it's free to try so give it a shot.

Developer Response ,

Thanks a lot for your review!

GreenThumb-420 ,

Works perfect 🌱☀️

Calibration is very accurate. just put in reference value with actual measured and the app is doing the rest 👍

Update: new version with calibration dialog walkthrough very user friendly. great improvement. thanks for the update☀️🌱

Developer Response ,

Thank you! We greatly appreciate your feedback.


Dominik Maglia
19.9 MB

Requires iOS 11.0 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating
In-App Purchases
  1. High Pressure Sodium Light $4.99
  2. Light Emitting Diodes Light $4.99
  3. Metal Halide Plant Light $4.99


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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