T12 Wavelengths / Lumens

cmpman1974(Zone 6 MI)December 29, 2010

I do not have T8 fixtures so let's forget that issue right now. I have grown lots of seedlings under fluorescents for years now.

What I'm curious about is whether one believes a Sylvania Cool White Plus bulb (4100k rated at 3,000 lumens) is better or worse than a Sylvania Sunlight bulb (5000k at 2,250 lumens). I put 4 bulbs over each shelf. Are the extra 3,000 lumens more crucial than the wavelength difference?

The difference in cost is $25 for a box of 10 5000k bulbs vs. $13 for a box of 10 4100k cool white plus bulbs.

I don't grow trying to get fruit indoors. I'm big into peppers, tomatoes and tons of other veggies.

I'm just wondering which would produce nicer seedlings if used. I look forward to replies/thoughts.

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Without a doubt, the 5000K bulbs. My favs are Daylight, which are in the 6,000-5,500K range. They produce much more blue spectrum.

Another "trick" is to keeps the temps as cool as you can, within reason of course. 55-60 degrees will produce short, stocky plants, provided you don't water with high N ferts. Tomato-tone is ideal for root growth and a $6 bag will last for hundreds of seedlings.


    Bookmark   December 29, 2010 at 7:30PM
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cmpman1974(Zone 6 MI)

Thanks Mike. I didn't know if lumens outweighed spectrum. it sounds like it does not. I have used 6,500k daylight bulbs w/success in the past that put out 2,160 lumens (T12s). Short, stocky is what I go for. I don't need tall plants. Space is important to me. :)


    Bookmark   December 29, 2010 at 10:37PM
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If you're only rearing seedlings and moving them outdoors after they reach a few inches, you should be fine with either bulb. If you were however growing them under lights to maturity, then the proper spectrum would be more important. You can always mix them as well... or shop at another store.


    Bookmark   December 30, 2010 at 9:36AM
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