My auto’s are around 8 weeks old and are in the 4th week of flower. My question is what’s a good PPFD and DLI for my lights to be at? My light is a VIVOSUN 450 watt LED bar style. My light is 24” from top of plants. I have a couple charts but I was wondering what others opinions was that has worked best for them? A couple of pics below of my two plants. I had some nute burn in the past so many leave tips are damaged. But I have the problem under control now. At least I hope I do. lol
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Minimum guidelines are:
Seedlings: 300 PPFD
Veg: 600 PPFD
Flowering stage: 800 PPFD
DLI is simply a measurement of PPFD over time. DLI can be maximized with autos by running 18/6 throughout the plant’s lifecycle.
I run my plants at 1,100 PPFD and get plants like this:
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Should I adjust my lights to at least 800 from now until harvest? Im in week 4 of flower. Im at 500 now and will need to turn my light up to 100% and lower the lights to get to the 800 mark. Should I adjust my lights gradually or just do it all at once? I wish I would have bought the 650 watt light instead of the 450 watt light. I’m going to have to get my light lower to my plants than I wanted to in order to get to the 800 plus numbers. I’m using the Photon App with their diffuser. I hope it’s close to being accurate? Thanks for your help. Your plants look absolutely great!
Be careful to not lower the light such that it heats the plant. If you can feel the heat from the light on the back of your hand when it is held at the canopy level, then the light is too close.
I make all of my light changes all at once.
Every light has a different spectrum. The downside of the Photone app is that it calculates based on an assumed spectrum and also fails to account for the complete photosynthetic spectrum. It accounts only for the visible spectrum of 400nm to 700nm. The photosynthetic spectrum is a bit wider at ~350nm to ~800 nm. Photone will be close, but not exact.
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What is your DLI at 18/6?
Don’t know. I’ve never calculated it. The light cycle is fixed, so PPFD is a sufficient measure.
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