A few weeks ago I traveled to Seattle Washington from my home here in
Portland Oregon (about a 3 hour drive) to a meeting of the Cascade Cactus
Society <http://www.cascadecss.org/> Quite a nice and friendly group of
folks. I traveled to Seattle because the meeting that month was to be at a
plant light store and the owner grows cactus. The store is called The Sun
Shoppe <http://www.indoorsun.com/> Owner Jerry Addington talked about
growing cactus under plant lights (he recommends Metal Halide). The ceiling
of the shop was filled with metal halide lamps. They were between 500 and
1,000 watt lamps. He quoted figures in the range of 2,000 to 5,000 foot
candles when using the metal halide bulbs. I am sure this is true, but the
bulbs were so high up in the ceiling, I was getting readings of only 250 to
450 foot candles on the plant stands where the cactus were displayed.

He did tell us that he buys his cactus and does not grow his own, and he
also tries to sell them off quick before they become elongated. He showered
us a few that had been sitting around the shop for a while and had not
sold. They looked bad. I thought he was a honest and helpful fellow and a
friend to all the cactus folks in the society. I did a little impulse
cactus buying while in his shop and I recommend a visit if you are ever in
that neck of the woods.

While taking reading with my foot candle meter in his shop, I was
approached buy a women (who's name escapes me) who told me she grows all
her cactus under fluorescent lights. She says they grow fine and flower. I
told her that when using a plant light (GE Wide Spectrum Plant and Aquarium
Light 48 inches (1220mm) 40 Watt) I was only getting about 200 or so foot
candles 4 to 6 inches under the bulb. She told me that she found a great
increase in light output when she switched from the cheap $9.95 "Shop
Light" fixtures, to a better brand with a better ballast.

She also told me that "plant light" bulbs put out little foot candles, but
do give off a lot of light in the red spectrum which is great when you want
to get a cactus to flower. She switched from plant lights to a combination
of GE Natural Color Kitchen and Bath Ultra bulbs (a "warm" light, with more
red than "cool" bulbs), and Philiph's Cool Home Light (3,200 Lumens, Color
Rendering index 70, Color Appearance 4100K).
When I got home I bought the best two bulb, 4 foot (1220mm), 40 watt
fixture (with out a reflector) that home Depot had for sale (about $25.00).
And the above two fluorescent bulbs. I also bought two other bulbs from GE
called "Sunshine Full Spectrum Lights (Simulates noonday summer sun, 2,250
lumens, color temperature 5000K, 90 CRI).

Ballasts......

A new ballast has been introduced called the "electronic" ballast. While it
is said that it can produce a little more light, it's real claim to fame is
that it is suppose to cut your energy use buy as much as 30%.
As a test I bought the best standard ballast Home Depot had for sale (about
$11.00), the best Electronic ballast Home Depot had for sale (about $16.00)
and a high end electronic ballast (about $40.00) from Grainger
<http://www.grainger.com> . I installed them in the best fixture I had and
measured the foot candle output in the center of the bulb after they were
on for about a 1/2 hour. I took all my measurements at about 4 inches under
the bulbs. I used the GE Sunshine as my test bulb.
In all cases (standard ballast supplied with the best Home Depot fixture,
best Home Depot standard ballast, and the two Electronic ballast), all my
reading were about the same; about 2,000 foot candles. I did get a little
more light out of the Electronic ballasts, but if I moved my foot candle
meter between 1/8 to 1/4 of an inch away from the bulb, it was the same.
Unless you about to replace a old ballast or your energy bills are high, I
would not spend the extra money on a electronic ballast. The best standard
ballast sold by Home Depot ($11.00) works just as well as anything else.

One thing about the Electronic ballast.....When you turn it on, the lamps
just come on immediately. No flickering. Very strange to see....

The cheap "Shop Light" fixtures that I was using did not even have a
ballast that I could replace. They had a transformer, a capacitor and some
other components at each end of the bulb. When i moved the plant light bulb
from them to Home Depot's best fixture, I *doubled* my light output.

In Anderson's "Threatened Cactus of Mexico" it says:

"Plants use light energy, but they need light of around 400 nm (Violet) and
700 nm (red) wavelengths, know as Photosyntetically Active Radiation
(PAR).....
As already indicated, it is necessary to use lamps that produce sufficient
PAR. The florescent tube lighting used for aquaria are suitable. Such tubes
are long lasting (+ - 18,000 hours) and they work at their best between 20
and 30 C. If the intention is to obtain only germination and initial growth
of seedlings prior to transplantation, it is enough to use only five
florescent tubes per square meter. This number has to be doubled if plants
are to be maintained under these conditions for a long time"

My growing area is about 1/2 of a square meter, and I have three, four foot
fixtures (1220mm) for a total of six lamps. So I am a little over the
recommendation (better to have more light than less). I have wrapped three
sides of my growing shelf with reflective mylar to reflect light back into
the growing area. All plants sit on a seed heating mat (about 85 to 90F (30
to 33C).

Sorry about the long post. Part two will be much shorter.

jack in Portland Oregon

http://www.users.qwest.net/~jhoneycutt/





























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