Orchids under fluorescent lighting?

[dlconner]

Hi, i had grow bulbs but they burnt out, or the thingy they were in burned out. whatever they don't work
now i have rigged up this thing to try and grow my orchids. i don't know if it's the same or if it will work. hence the post.
i have two GE 42 Watt (150 watt equivalent) bulbs and three GE 26 watt (100 wt equivalent) the two big bulbs burn yellowishy and the three smaller ones burn bright white. there are 5200 lumens total of the yellowish light and 4800 total of the whitish. grand total of 10,000 lumens. i don't know if the spectrum is correct, though or if that is even enough intensity. what is degrees K? i saw others talking about it on another forum. how do i determine that? how long should my lights be on? how close to the plants should they be? etc. etc. there has to be enough light in here to grow SOMETHING. but i heard orchids need red spectrum, which i'm sure is absent in the "daylight" bright white bulbs.
these are all fluorescent that you would screw into an ordinary light bulb socket. like old incandescent. so help me out if you can.
thanks.
LEE

[Gold3nku5h]

Well, thats alot of light for idk how many plants... Since they dont get too hot, i would think about 6 inches away would be fine. Farther away about a foot would probably be ok if you have some kind of reflective material going on in there.. Color spectrum that we try and use for growing are 6500K for vegetative and 2700-3000K for flowering. Anything within probably about 3-400K either way from 2900 and 6500 would still be fine.. 10,000 Lumens is pretty intense, so you should get really good growth.. I'd look into a nice reflector/hood or some kind of grow space with all that.

[mojomick]

I'm not sure about the yellowish, etc. I used to grow in the house under florescents. I used 2 warm white and 2 cool white and they meet the color spectrum needed for orchids. I had them anywhere from 6 to 12 inches above the plants depending upon the kinds of orchids on the tray (low light, medium, etc) I borrowed a light meter and checked out the light at each level. Anyway, I ran my lights 12 hours in the winter and then progressively increased the light until I was running 16 hours in summer and then started decreasing again toward fall. I have a greenhouse now, so don't have to worry much but this schedule worked well for me for years. Betty

[CoolPhrog]

Lee, I moved your thread to a higher traffic area :-)

[Tim C.]

Lot's of questions, so I'll do my best to answer them all.

"What is degrees K?" - This refers to the color spectrum that the bulbs put out. The lower the degrees K, the redder the spectrum. The higher the K, the bluer the spectrum.

"How do I determine that?" - I'm assuming you're referring to determining the K readings on each bulb. The package you bought the bulbs in should have all relevant light readings, including degrees K, on it. If the bulbs are burning yellowish, they're around 2700K, clean white light is around 5000K, and slightly bluish light is around 6500K.

"How long should my lights be on?" - Depends on how many footcandles (a measurement of light intensity at a particular position/distance from the light source) your lamps are putting out. Most orchid growers I know use 10 or 12 hour days in the winter, and 14 hour days in the summer. I personally use 12 hour days all year round.

"How close to the plants should they be?" - This would depend on how many footcandles of light you get, and what distance from the bulbs you get those footcandle readings.

"i heard orchids need red spectrum which i'm sure is absent in the "daylight" bright white bulbs. " - Orchids need red light mostly for flowering, though they absorb all parts of the light spectrum, even some green. Most light gardeners I know use a mix of bulbs - 2700K and 6500K - to provide a full range of light to their orchids. The daylight bulbs still have output in the red light spectrum, just not as much output as the 2700K warm white bulbs.

And just to give you a comparison, here are the stats of my grow area and light setup, and what I grow using it:
- 27" deep by 49" wide by 3 foot tall.
- 2 GE Daylight 40watt T12 fluorescent tubes, 6500K, 3050 lumens per bulb.
- 2 GE Kitchen and Bath 40watt T12 fluorescent tubes, 3000K, 3400 lumens per bulb.
- 3 Bright Effects Daylight 26watt compact fluorescent bulbs (the screw-in type you're referring to), 6500K, 1600 lumens per bulb.
- 3 Bright Effects Soft White 26watt compact fluorescent bulbs, 2700K, 1750 lumens per bulb.

All of this comes to roughly 23,000 lumens in my grow area. My footcandle (FC for short) readings are, in distance from bulbs: 5" = 5000 FC, 10" = 3500 FC, 18" = 1500 FC. I grow standard sized Catts in this setup, their leaves all sit within the 3500-5000 FC range at all times. No scorching, no burning, nice green leaves with some purple edges. Lots of big blooms.

I urge you to find a light meter that will read footcandles in both sunlight and artificial light. I got mine at a local hydroponics store for $22. Once you have the meter, take some readings at different distances from your bulbs, and you'll know how far your plants have to be from them. And remember: because artificial light is constant, your orchids don't NEED to have the full recommended FC amount. I've bloomed mini-catts under just 2000 FC of light, and they've bloomed nicely, even though the recommended FC amount is 3000-3500.

Hope I've answered all of your questions, let me know if you have more.

-Tim C.