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Growing under Lights

Growing cool-season vegetable under metal halides

12 years ago

I'm new to gardening and am planning to grow some leafy greens indoor. I posted a while back about using indirect daylight from my north-facing window, and realised it will be insufficient to grow any plants at all. So I'm now planning to add several metal halides to supplement the window light. I had been researching on how to grow most of the greens, and noticed they are all "cool-season vegetables" (collards, mustards, cabbage...etc). From what I understand, metal halides do produce quite a bit of heat, and cool-season vegetables will bolt and taste bitter if subject to warm temps. My indoor temps are in the low-80s during summer, even if I install a fan to increase ventilation for the plants, I don't think I can get it much lower than that (maybe able to get that down to mid-70s). Do you think that is good enough to grow the vegetables listed above? There won't be any direct sunlight hitting the plant or the soil.

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Comments (5)

wordwiz
12 years ago
Why use a flame-thrower when a small propane torch will work? (Not to mention - why grow indoors in summer?!).

El cheapo shop lights, with daylight bulbs, will work perfectly well, put out little heat and provide nearly the same PAR light the MH bulbs will (about .0003 factor per foot candle). The same wattage will cover 30 sf. and despite what the MH sellers claim, a 400 watt MH, even one rated at 36,000 lumens, will not. At best, half of that.

Mike
milocrab
Original Author
12 years ago
Forgot to mention in my first post, I live in a north-facing apartment with no balcony and close to zero direct sunlight. The windows (bay windows that are 1.5m in height) are unobstructed and huge though, so I thought I could install several permenant lights on the ceiling, and use them for several hours each day to make up for the minimum light requirement for some greens.

I do have a lux meter and have read about Daily Light Integral. For growing leafy greens, I think I can get away with about 12-14 mol/day. I get about 5-6 mol/day just from the diffused north window light. So I figured if I switch to artificial lights when the sky starts to get dark, I could make up for the extra 6-8 moles needed.

To be honest, I went for metal halide floodlights, because they can be installed on the ceiling and still provide enough lux at approximately 1m distance. With fluorescents, I'll need to add a rack in front of my window and have the lights placed very close to the plants (which will also block out the diffused window light). I just thought MH will work better in my situation.
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wordwiz
12 years ago
milo,

If your aim is to get six mols per day, you will additionally need ~2,000 footcandles for six hours or 1,000 FC for 12 hours. Are the bulbs you are considering bright enough to provide that much light from three feet away?

Mike
milocrab
Original Author
12 years ago
Mike, I ordered 2 narrow-angled floodlights (from Iwasaki) that are 150W each. According to the information on their website, it can light up a 50cm diameter area with approximately 90000 lux (~8300FC) at 1 meter. If the info is more or less correct, and considering the light intensity will fade out fast outside the beam angle; I'll probably still be able to make up for the 6-8 mols with an extra 3-4 hours in the afternoon. Fingers crossed that these floodlights do produce as much lux as it is advertised. :)
wordwiz
12 years ago
Milo,

If the works as advertised, they should provide plenty of light. Let us know what kind of reading you get!

Mike

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