[CH] Re:] yellowing under artificial light
Alex Silbajoris (asilbajo@hotmail.com)
Wed, 17 Oct 2001 13:28:58
>From: "Karen Stober" <kstober@us.ibm.com>
>What am I doing wrong? The lights are about six feet up on the
>ceiling, the pots are on the floor.
K -
Think of it from the perspective of your plants - actually imagine laying
among them and looking up at the lights. A flourescent bulb is about as
bright as a bright daylight sky, which is what your plants want. If the
lights are six feet away, what percentage of the "sky" in that room is
actually lit, and how much of it is dark? That is, as seen from the view of
the plants, are the lights just bright strips against an otherwise dark
background?
Then imagine the view with the lights just six inches away. Now the "sky"
is almost completely lit because the light fills much more of your field of
view.
There's something called the "inverse square rule" that describes how the
apparent brightness of a light source diminishes with increased distance:
http://www.intl-light.com/handbook/ch06.html
(This helps explain the presence of extra driving lights on my Escort's
bumper.)
Try lowering one light until it almost touches the plants. Flourescents
don't get very hot, so you don't have to keep them back as you would a hot
halogen or other incandescent lamp. If you can adjust the height of the
lights, you can let the foliage "chase" them upward as it grows.
Can you build some kind of white box around the plants, so light that would
otherwise have gone into the room is reflected back onto the plants?
Also, do you have any provision for forced air circulation?
- A
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp