Date: Thu, 30 Mar 2000 22:03:22 -0800 From: Stephen Davis <stephend@ricochet.net> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg942$foo@default> Subject: Re: Artificial LIGHT, Ultraviolet and plexiglass / glass
Matt,
>Hey CPers,
>
>I was just discussing artificial terrarium lighting with another CPer. He
>feels that the glass and plexiglass covers I use on top of my terraria are
>blocking what he says are ultraviolet wavelengths essential to many plants.
>He instead uses saran wrap on top of his terraria and is convinced a thin
>material such as this (or no cover separating the lights from the plants)
>are crucial to good plant growth. While my plants grow pretty well, I cant
>help but think I could get better results if I made some changes....
I didn't know plants "needed" UV. I do remember some of the news
footage from the foot of South America after the Ozone hole was
discovered, showing plants turning very red with pigments to protect
themselves. They insinuated that this was not good, but frankly, and
unfortunately, the press is not the best source of information out
there.
>I also recently replaced my bulbs as it had been a while. I've been using 2
>cool white, 1 warm white (bathroom and kitchen), 1 "plant and aquarium".
>whats everyone else using? anyone know of a reason I should change this
>mixture? its what my buddy phill mann recommends.
>
>Anyone have some input on this?
I just use cool white, and most of my CP look great, as long as I
remember to water them. However, I realize you are trying to pull
every last inch out of them.
What about Halogen lights? Hot, but they are bright and are full
spectrum, including enough UV that you have to use a glass UV filter
on them.
I've been trying to wrestle this with your question for a few weeks
myself. On top of that I have a few more issues. I just got a glass
edwardian case 19"W x 19" D x 22" tall growing area. The whole unit
is 7' tall, with a shelf below the case, and a place for plants above
it. The case itself is at eye level. I've been looking at compact
lighting to put in it. The top is metal and I want to put plants on
top of it. Normal florescent won't work because of size constraints.
The under cabinet ones might work, but the ones I found were very
small lights in relatively big fixtures, and I didn't think they
would put out enough light.
The two solutions I'm looking at are:
1) Under cabinet Halogens. 2) An outdoor florescent spotlight
The under cabinet Halogens are 2.5" across and only 1" thick. Each
bulb is 10W. They could be hung on the bottom of the metal top
section very easily. The problem I see is heat build up. I'm not sure
how many I would need, but at least 3 or 4 would be required, maybe
even 5. The light has a spotlight type reflector.
I plugged one in and can feel warmth from about 5" away. But it's not
too hot. However, get 5 of them in an enclosed area on a hot day and
there might be a problem. to see them go to http://www.lusa.com
2 - The florescent is an Electronic Outdoor Flood light. The large,
flat rectangular lights you often see on the outside wall of a
building, pointing down, or out at a 45 degree angle. It uses one of
those new 35W, four tube compact bulbs. The tubes are all connected
at one end only, and are arranged like greek columns, side-by-side.
The whole unit is a little over 1'L x 8" wide, by 4.4" deep. Length
and width wise, it's perfect. But it's way too thick, unless I cut a
hole in the top and have it poke up through that. It also has a great
mirror reflector. It would be fantastic to light taller plants or
even have several of them surrounding some plants for very bright,
fairly even lights. However, at $49 each, they ain't an $8.99 shop
light.
I thought the light specs were impressive. They claim a 200 watt
light equivelent, Tri-phosphor bulb with a color temp of 4,000
degrees kelvin, CRI: 84, Lumens of 2,700. I have no idea of what CRI
is, and I don't have any books talking about the degrees kelvin best
for plants. Does anyone out there know anything about this stuff to
translate? Is this a great light that I should try to use instead of
the halogen?
>Do we know what wavelengths of light CP prefer? Does a glass or plexiglass
>cover prevent any of this light / specific wavelengths from getting to the
>plants?
You are right about the UV blockage. Glass kills it pretty well.
>Please respond, I think this would make for a great discussion
>topic!
More on topic than the animal one anyway. :-)
I agree. Perhaps some co-ordinated experiments would shed some light
on the subject too.
>
>Good growing!
>Matt
>
>Growlist, wantlist and other nonsense...
>http://www.geocities.com/sundewmatt
Stephen Davis
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