Why is the minimum ammount of lumens suggested 3000 per plant?
as posted by roseman
Light seen and perceived with the human eye is measured in Lumens. There is an ideal amount of lumens for growing and a minimum amount of required lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use. (Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer day).
answer ? hopefully
Lighting Fun
by "Roger S. Miller" <rgrmill/rt66.com>
Date: Mon, 1 Jun 1998
>Randall states that blue light produces bushy, short plants, something I
>have read many times in the past. Thinking that I would like my plants to
>have this growth ectect .....
watts vs. lumens
by Wright Huntley <huntley1/home.com>
Date: Mon, 15 Mar 1999
an excerpt
> Lumens is a measure of what comes out as light ( candela/steradian) and thus
> better, but far from good enough
This statement is quite misleading, and lies at the heart of a lot of the
misinformation we encounter here on the APD. Lumen is a psychophysical term that
describes the way *humans* perceive optical radiation. Candela is a member of
that same photometric system. They are defined in terms of the human observer,
and not the source radiation. They tell you next to nothing about what actually
"comes out."
Here in APD we define light in a much broader sense, usually. Lumens *are* great
for predicting how bright the light will "look." Too many lumens per Watt always
cheats the plants out of energy *they* need, for the manufacturers of "cool
white" tubes have gotten really very good at not wasting red and blue light we
don't see well, anyway.
Red and blue are about 20% of the output of a very high lumens/Watt tube.
Unfortunately they are about 80% of the photosynthetically active spectrum of
our plants. That's why plants *can* grow well under "cool white" lights. You
just may need several times as many Watts of it.
Wright
so my anwser in laymens terms
it was suggested for smaller plants . so not to dry or bake the little darlings
plants dont see light we do
if prroper light spectrum is used its more efficient