Update on CFL Setup....after using light meter...this is kind of long!

[Austinerd]

Hello All,
A week or so ago I posted a thread about my CFL setup which has a 200-watt (5000K) bulb. I posted another picture here....sorry about the pic quality (had to get it to fit the forum limitations). The light carts on either side of the middle unit have standard shop-light type fixtures (2 40watt tubes on each fixture), tubes recently replaced. I have 3 phals under the left one and a pyschopsis. Under the right one I have a couple of phals. Under the middle CFL fixture I have:

Slc. Hsin Buu Lady 'Y.T.'
Blc. Haw Yuan Beaty 'Hong'
A NOID which I suspect to be another small Blc.
My newest acquisition: Pot. Love Passion 'Orange Bird'
Onc. Sugar Baby
2 Onc. NOIDS

I just got a new digital light meter today, recommended to me by Ross. It's the Light Meter Lux & Foot Candle - Sper Scientific 840020. IF I'm using the light meter correctly, the results are a bit disappointing...but confusing also. Under the standard fixtures (where I have the phals) I'm getting leaf-level readings of only 150-200 foot-candles. Under the CFL fixture in the middle, (all leaf-level readings) I'm getting 6-700 foot-candles on the left end and around 500 on the right end (I keep the oncidiums at the ends). In the center, where I want the catts to bloom, the maximum reading I'm getting is about 1200 foot-candles and this is directly below the bulb, about 8 or 10 inches down.

Soooooo........I'm a bit confused because my books say the phals want 1-2000 foot-candles, and Ross is thinking I should want about 1800 or so for the catts. (They run about 13-14 hours per day by the way). But my phals are perfectly happy and have been blooming. I'm wondering if I need to lower the CFL closer to the catts or wait and see.........

Sorry this is so long, and thanks in advance for any suggestions or comments.
Dan in Austin

[Ross]

Dan, I believe the light meter is correct. I also would bet the leaves on your plants are nice and deep green (am I right?) There appears to be room to move the plants closer to the tubes, or the tubes closer to the plants. Either one will yield higher light levels. As for the regular florescents, they really are that dim. Your eye might perceive them as bright, but the light meter is correct. If this were my setup, I'd consider more lights, or more powerful lights. Hope this helps.

[Austinerd]

Thanks, Ross....you're the one I was hoping would reply to this. It definitely helps. I have since moved the plants a bit closer to the light and getting higher light readings. They're still not quite at 1800 footcandles but I don't want to shock the plants too much yet. I'm still curious why my phals seem to be happy under the T12's....given that they're so dim. I guess they're adaptable.
Thanks, Ross.
Dan

[Austinerd]

OH...and to answer your question, the leaves are in fact fairly deep green. When I have another chunk of change to drop on my plants I am going to get a 48" T5 fixture to replace one of the dim shop light fixtures for the hanging cart.
Dan

[10010100102]

Are you sure it's 2000 footcandles the Phal's want and not 200? Maybe I'm wrong, but I seem to remember reading 200 fc's for phal's somewhere... If it is 200, that would certainly explain why your phal's are doing so well.

[Austinerd]

Hi Joseph,
I have a couple of books (Miracle-Gro and Ortho's) that both have a graph showing that phals need 1000-1500 footcandles....and that does seem high. But in any case, I guess there's no urgent need to increase the light for the phals. I have 3 blooming now so all is well under the dim lights.
Dan

[calvin_orchidL]

Hey Dan

I would agree that your light meter sounds accurate. The thing to remember though, is that the statement about phals needing 1000-1500fc of light doesn't mean 1000-1500fc for 14 hours straight. Also, some references might not be perfectly accurate (and even phals come in many shapes and forms )...ie I've been cooking my aeranthes grandiflorus under much higher than the recommended LOW light, and it's popping out the spikes like no tomorrow. Conversely, I know people who have phals on north windows that receive the crappiest light ever (or even worse, behind shear curtains in shady living rooms)..and they get bloom after bloom. How, I don't know. My noid phals bloom under 500fc conditions, but that's measured by a cheap light meter so who knows if it's accurate. I do find it incredible, though, that with our fancy light meters and light setups, we struggle in places where others succeed with little to no effort. If your plants are happy now, you might as well let them be. If you do want to experiment a bit, a nifty thing to do to increase light levels for individual plants is by putting the plant on a small box to raise it up...then put it on a higher box after a month or so if you see it responding positively.

The one caveat is that if the plant is naturally in a resting stage of it's life, it won't respond much in the form of new growth, and might end up getting baked...but phals don't really rest so you're in the clear with them. Catts, you might want to observe closer once they put out new growth/roots...just for a bit of reference, when I had my 65W CFL, I had the catts 3-4" away from the bulb....which meant I could only fit about 3 plants under the light....leading me to follow to Ross' sage advice and go for T5s..haven't looked back since. Your CFL is bigger so you can probably get away with it, but you might want to add a few smaller supplementals. Good luck and welcome to the wonderful controversial world of artificial lighting

[Magnus A]

As Calvin explains this kind of high light is NOT continuous light for 14 hours.

MOST of these are highest light level received at the natural habitat at noon.

This is often mistaken as a mean value over the day OR the maximum light level that the plants can handle.

[Austinerd]

Thanks Calvin and Magnus.....so I won't worry about the phals. I did buy an additional CFL (a cheapy from Lowe's but it said 2900 lumens) and moved the catts closer to the CFLs....now I'm afraid I might cook them because the light meter is now reading around 1500-2000 footcandles, and they're on for 13 hours. Maybe I should pull back a bit. I just really want my mini catts to bloom! Will keep you posted. Thanks for the input I really do appreciate it!
Dan

[calvin_orchidL]

Please keep us posted! I learn new things about growing under lights all the time, and love hearing about other people's experiences.