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How much PPFD does a plant need when it is a seedling?
cellardwellar420
Well-known member
The tent size makes no difference at seedling stage its mostly about the light my friend look around theres plenty of info in this site best of luck with your grows..
Thank you so much; I appreciate your help
It's so detailed for me, thank you so much for your help
It doesn´t matter, PPFD alone is not useful at all to measure how much light your plants get.
It´s just saying how much light there is at a plane.
You can get a certain PPFD value on a area with 10 Watts or 1000 Watts, depending on the distance of the light.
If you use PPFD you always need to add the distance, PPFD alone is useless.
Hope we get rid of this value in the growing community soon.
Orange's Greenhouse
Active member
You're mistaking PPF with PPFD. PPF is total light output (number of photons per second). If you spread the same number of photons over a larger area you get lower intensity. It's useful to size lights. If you have 10 m² of canopy you need atleast 10000 umol/s of output.
PPFD is normalized for area. By having the (equivalent) area in the measurement it doesn't matter what distance the light is at. That allows it to compare measurements between facilities/studies without calculations.
I don´t think so
What do you mean with "normalized" exactly ?
Orange's Greenhouse
Active member
It takes the light output and relates it to the area of the sensor. PPF is umol/s and PPFD is umol/s/m².
I don't understand why you think it is useless? If a HPS hangs 4 m high or a quantum board is 20 cm above the canopy. The target PPFD is the same.
