Footcandle light readings in Orchidarium

[Becca]

I bought a digital light meter a while back ago and decided to see what readings I got on my lights in my new orchidarium....I would assume that the lights would be suitable for orchids being it is an orchidarium......this is what I get....

3000 FC is the highest I can get to the lights....but that would mean my plants would have to be smack against the acrylic glass....doesn't seem strong enough to me for my Cattleya's......hmmmm.

And at the bottom where I have my phal's (which I just burnt outside) it reads around 300 to 500 FC.

I have read that bright to highlight plants need 3000+ FC to bloom.....I have so many bright light orchids that I don't know what to do.

The bulbs read Sylvania Delux L 55watt. I have 3 fixtures with 2 bulbs each. Each contains a warm and cool bulb.

According to the Orchidarium Inc.'s website I am supposed to have six 21", 4800 lumen, high intensity, bi-axial lamps.

I know that lumen and FC are different measures of light, but my meter only gives me a choice of LUX and FC.

Any suggestions or am I just over reacting....I want my 'chids to bloom for me someday, not just grow!

Here is a link I found with the specifications of the light bulbs:
FT55DL/830/ECO - Sylvania 20590 - 55 Watt - 4-Pin - 2G11 Base - Compact Fluorescent Light Bulb

[Jeremy]

I would do is to try out the lights and experiement with them. The plants will tell you whether they are happy by obviously blooming, but also by leaf color. The leaf color should be medium green (grassy green color) and not dark green. Another way that I use is look at the light reflected off the back of your hand and compare that with sunlight reflecting off the back of your hand, and look how your hand is illuminated. Another way, I am not exactly sure if this works for artificial lights, is the look at shadow of your hand on the blank sheet of paper. For Cattleyas, it should be a sharp shadow. And for phals it should be a fuzzy shadow. Good luck

[mayres]

I'm hoping to try a fixture with 6 tubes similar to that this winter. Duration of light is also a factor. When you leave your lights on 16 hours a day the effect is cumulative. Natural daylight is more varied (obviously) with the more intense light at the middle of the day. To get more intense light than those T5 tubes you will need to start thinkin HID - metal halide or sodium vapor.
Here is an excellent culture guide with a section on lighting that you might find interesting. Comprehensive Culture Guide—Light levels for growing orchids Enjoy! mike

[Becca]

Thanks Mike,
I was just looking at that website earlier and found it quite interesting. Well so far my orchids have only been in the orchidarium setup for about 3 weeks now....wow time flies....so as Jeremy mentioned above....at least I can try and look for signs by watching my orchids. It is just really hard for me to tell since the light to my eyes is much brighter, so there for the greens look much brighter, and that may not really be the case. Maybe I will look into a book on growing orchids w/ artifical light. One thing I think I may have problems with is if I ever want to switch light bulbs, I think I would have to buy new fixtues as well. I haven't found many 4 prong lights.....but maybe I am just not looking hard enough!

[Ross]

Becca, I think you are worrying over nothing. 3000FC (actually more like 2000 down by Cats) is more than enough when you consider the light recommendations are the highest at around noon outdoors and dim at sunup and sundown. Yours run full bore the whole time its on. Light is acumulative over the "day length" 300-500 at leaf surface for Phals is OK. They can take constant light up in the 1500-2000 range, but will do fine below that. The other thing is that light meters are approximate and rarely very accurate - even in a camera.