Jeffrey Barker wrote:

Ok. This is not a troll, and I really hope it doesn't seem that way.
I'm planning on getting a grow light for the first time this season,
after doing some mild indoor and outdoor gardening for a few years.

The whole thing about putting the light so close seems a bit
confusing. (I'd like to use just one or two lights for all of my
plants so I don't have to spend a fortune on lights.) The SUN is
pretty far away, so why is it such an issue to have the lights so
close to the plants? I know the answer is so they don't stretch out
and get spindly, but why does artificial light have that effect? I
know this must seem like a really idiotic question, but none of my
gardening friends seem to know the answer.
Jeffrey

The simple answer is that the sun gives off a *lot* more energy than a
fluorescent lamp. So to compensate, to have to place the fluorescents a
lot closer to the plants than you would the sun. People will probably quote
the "inverse square law" of light intensity to you, but it doesn't really
apply because the flourescent tubes do not resemble a point light source
(the sun *does*, however, from this distance); just the same, the light
intensity drops off dramatically as you increase the distance from the
source, even if it's not as bad as "energy decreases proportionally to the
distance squared". :-)

There are other issues as well, such as color spectrum, and photoperiodism,
but you don't need to know much about that -- just don't leave your lights
on 24 hours a day or you'll confuse some plants.

Best regards,
Bob

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