Photon needs of each species of plants

PilouPilou

PilouPilou

Well-Known Member
Hi guys!

I'd like to find an online manual or studies where are written the photon needs of each species of plants.. something else than cannabis^^

If someone has a link thanks in advance!

Cheers!
 
wietefras said:
It's a curve. Not just a single value. You can grow Cannabis anywhere between 200umol/s/m2 and 2000umol/s/m2. Same holds for other types of plants
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From what I have just found, DLI value could be better than a single ppf/ppfd value...? Now I don't understand why we need to calculate DLI from the PPFD because PPFD is an area value and based on the height of the light.. it's an other question that I need to understand!!
 
PilouPilou said:
Now I don't understand why we need to calculate DLI from the PPFD because PPFD is an area value and based on the height of the light
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That's pretty much like saying you don't need to know how fast you were travelling to calculate the distance you traveled. "We traveled 4 hours, how far did we go?" ummm... how fast were you going? :)

So to calculate DLI you need to know how long the lights were on, and also how how intense was the light source.
Ppfd is the measurement we use to denote the intensity of light.

Also the reason it is given as falling over 1 square meter is that we need a common unit of measurement.

When listing your speed you always use a common unit of measurement to simplify comparisons and calculations. So you use mph or kph, you never say that you were travelling 60 miles per 1/2 hour, or 30 miles per 20 minutes.
 
PilouPilou said:
because PPFD is an area value PER Second and based on the height of the light.. it's an other question that I need to understand!!
Click to expand...

DLI is just an extended version of timing your photon quantity ie put so much per second in this space and then calculate those seconds into a day for DLI.
25-35+ DLI is what I have seen for cannabis.....varies.
 
DLI is more an issue for plants growing under changing light sources.

In our case we usually just switch on the light and it's the same intensity all "day". Just knowing that intensity is then enough.

For instance the sun isn't at the same brightness all day and then you can't just multiply time by a known intensity. You need to sum up all those different intensities over the whole day to get the total amount of light the plants received.
 
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