How many 55w PL-L lights for my orchidarium

[ChrisAZ]

I need to light an orchidarium that is 45"tall 30"wide and 20"deep. I plan on using 2 or 3 55w PL-L's with individual reflectors. Each 6500k bulb is about 4800 lumens. Can anyone give me an opinion on how many bulbs to try to pack in a custom built hood .Is 2 55's enough? Is 3 too much? Are the 6500k's the way to go? The ballasts will be mounted away from the enclosure to reduce heat and the bulbs will be fan cooled within the hood, behind glass. I'm not sure yet on exactly what all I'll grow in here yet, though I hope to be capable of a decent variety being that the light level will vary quite a bit from the top to the bottom of this 45" tall enclosure! Any suggestions?

[Tim C.]

I'd try to squeeze 3 bulbs in the hood if possible. When I grew under PL lights, I had 4 of them, mounted over a four foot tall, three foot wide, by two foot deep acrylic case. I used plastic covered wire shower caddies to form little shelves along the back and sides, to give smaller, more light-demanding plants the light they needed. Even at four feet from the bulbs, I was able to bloom Phals and Oncidiums on the bottom, and mini-catts on the shelves, which were about two feet from the lights.

-Tim

Edited to add: I've always grown under 6500K fluorescents, so that's the way I would go.

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[ChrisAZ]

Thanks for taking the time to share your experience Tim. I've been looking for someone with actual experience with what I'm attempting here. 3 lights it is. What kind of reflectors did you use and what about heat and ventilation? Do you use different lighting now or just no longer have the enclosure?

[Tim C.]

I used individual reflectors, ordered from ahsupply.com. Their reflectors are very nice, and definitely put a lot of the reflected light back into the growing case, as opposed to it being absorbed by the PL bulb. I don't use PL bulbs any more because I no longer have the case they were on. I tore it down several years ago, and my lights got lost in the subsequent move down here to Florida.

As for heat, I really didn't find it to be a major issue. The hood mine were in was made of wood, and had about two inches of space between each of the top boards. There was a noticeable amount of heat coming from the lights, but it wasn't of any detriment to the orchids or the Lexan top of the growing case. I don't know if a PC fan would cut it with 55 watters, since they'd be so long. Maybe try to find a small, clip-on fan and aim that bugger right at the bulb enclosure.

-Tim

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[bartboogmans]

I am also trying to make an orchidarium.
I was planning to use 1 18w(6500 K, 1300 lm) Fluorescent tube lamp.
but i am starting to doubt this plan when is see that others use much more powerfull lights.
my orchidarium is positioned in front of a west facing window.
i used an 16''h x 16'' l x 32'' aquarium, and the lamps will be placed approximately 10 inch above the orchids.

is 18w way too little to use?

[Tim C.]

For a tank that size, I'd definitely say that 18w is too little light, especially if the light fixture is hung 10 inches above the orchids. The ideal situation would be to have enough light to place the fixture directly on top of the growing case/orchidarium, and still give all of your orchids enough light to grow and bloom.

What kinds of lights do you have available to you? What kinds of orchids are you wanting to grow? For a space that small, I'd say either make your own CFL (compact fluorescent - the spiral type bulbs) setup, or find one available for sale. CFL's are great for putting a lot of light in small spaces.

-Tim