How many lumens is too much?

hmanmcgee

Active Member
How many lumens per square foot is absolutely too much for a plant? I know it may very with seedlings and clones and what not, I am wondering for strong plants, around 1 foot tall, what is the absolute highest lumens you can put on them, or is the only limit the heat you produce with the lights?
 

Serotonin

Well-Known Member
I think there is a level at which the chloroplasts can be totally saturated with light and thus leading to a waste or excess but I think heat would ultimately be the limiting factor since you're only going to get that type of output with HID's.
 

budman56

Well-Known Member
If you're new to growing you should get a growers guide that is for indoors. Marijuana Growers Guide by Ed Rosenthal goes into the whole story about light and how much
 

pastafarian

Well-Known Member
i cant imagine you over doing it unless your plants are burning white hot as long at they arent yellowing/browning dont worry.
what u got a million watt ultra hps?
 

hmanmcgee

Active Member
I've just got a small space and am thinking about putting 11,000-13,000 lumens/sq ft on my plants. I know the sun is 10,000, and I didn't know if going too much higher would for some reason oversaturate the plant with light. I think 11,000/sq ft. will be more than enough and cheaper for me anyways, so thank you all for the advice.
 

T.H.Cammo

Well-Known Member
there is no such thing as too many lumens for established plants, only too much heat
I would tend to agree with Weediscool. But the truth is - I don't really know that for a fact! Light is one of the "Limiting Factors", just like water, temperature , nutrients and atmosphere (co2); that is to say that "less than optimum of any of these will effect growth in a negative way". On the other hand - too much of any of these will have the same effect - at some point you can reach toxic levels of just about anything!

I think it is highly unlikely that "normal" people would use "that much" light, it's just too expensive. There is the issue of "Diminishing Returns", or wasted light.

Cannabis doesn't obsorb light the way a shower drain obsorbs water, that is to say that the higher you turn the water - the more water goes down the drain. Cannabis leaves are covered with microscopic light receptors that act vary much like a Venus Flytrap plant. These light receptors gobble up a single photon of light then "shut down" while they "digest" the light and pass on the energy. In other words, the individual light receptors are "on" part of the time and "off" part of the time - it wont soak up more photons while it's "off", so the excess light photons are just wasted.

How much is too much? It's hard to say exactley! But I would say that not too many people use more than 80-100 watts of HID lights per square foot because of diminishing returns.
 

T.H.Cammo

Well-Known Member
I have just over 10,000 lumens all with CFL is that ok
It's purely a matter of "How much Light - vs. - how much Space". If you've got 10,000 lumens lighting up a 1 sq. ft. footprint - then yes - that's probably excessive! If you've got a 2 sq. ft. footprint - that's just about the right amount of light for that area. If you've got 3 sq. ft. or more, then I would say "Get more lights!".

Since you are using CFL's, it is most important to know that you are using the proper spectrum (the proper ratio of 6.5 K and 2.7 K CFL's) for the growing stage you're in. Some people think CFL's are "all the same" - they're not!
 

Dr. Who

Well-Known Member
Well for the sake of the newbies who will look at this.

1: lumins are not a good way to measure plant lighting needs!

Once the lighting intensity gets to the point of the strength of the sun. The plant (any C3 plant) will at a point in the day. Reach what is called the "light saturation point".
This begins to effect the plant earlier (in the day) then many think. At that "point" the plant begins to change on the cellular peptide level to "protect" it's self from the intense light of the day. At night, the plant reverts or changes back to the original 100% light receptive "mourning plant". This effect reduces photosynthesis and therefor overall plant growth by as much as 35%......The use of Co2 counters this effect and what you are doing is recovering this 30+ percent by delaying the "saturation point". Thus allowing the plant to photosynthesize at it's full rate...

There, now you learned something today!

This is natural and does not "hurt" the plant.......

Spectrum is important, just like intensity!
 
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