1st time grow Unknown/ unmarked seeds trial run

Good work on finding it and correcting the issue. Phone light meters are not accurate but they are consistent if using the same paper lens defuser and phone. Then just base the ideal light on the internode growth of the plant and make note of what the phones PPFD reading is. It might say anything from 400-800 but realize its not an real reading of the lights intensity in PPF and for your purposes its just to establish a standard with the app. the D in PPFD stands for density, so unless your inputting your tents sizes and taking multiple readings and averaging it out. it is really only recording a makeshift calculation from lux to PPF. And if anything a basic Lux meter will be more accurate and you can do some fancy math to get a better estimation of your PPF/PPFD. I used a quantum par sensor in my tent I borrowed from a buddy. The reads where intense, way more power then I was expecting and with the door closed vs open it was even more. Some dude made a video on youtube comparing different brilliant white papers with the photon app on iPhone camera and the different readings. I think the best one as stables house brand and he compared it to a quantum par sensor. However I do think it was calibrated before hand or he paid for the pro version of the app to work with LED's. When I tried the app on an old phone, new one and a iPad, they all read different values with the same paper sample used, anywhere from 350-900. massive range. But now that I know my real PPFD for the tent I can set my phone to say the approximate PPF for the hang height I tested.

New plants like this do not require much light. Download a PPFD App on your phone and you should be around 300-400 PPFD at this stage. Depending on what soil you used. Feeding should be very very light for the first few weeks.