Onion and lettuce under T5 or T8 fluorescent lights

11 years ago

So, i want to grow lettuce and onion under either T5 or T8 lights, i mean i'm not sure whether T8 will work fine or i should get T5. The lights must be full spectrum, right? In my country there are virtually no T5 full spectrum lights(or atleast not powerful enough), only T8. So, there is SYLVANIA ACTIVA F58W/172 T8 and SYLVANIA ACTIVA F58W/965 T8, those are the most powerful T8 lights that i've found. What is '172' and '965' respectively? What does that mean? Is it important? The CRI of those lamps is RA98, which is good, right? Those lamps give about 3700 lumens and are 150cm long(5 feet), so how much of them should i use in order to cover an area that is 1.5m(5 feet) long and 1m(3 feet) wide...if possible at all. I can get T5 full spectrum if needed, no problem, but do i need them or T8 are good enough for lettuce and onion?

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Comments (3)

klinko16
11 years ago
You want FOUR foot lamps, NOT 8 feet!!!

find out if you can purchase lithonia F40T12 four foot strip light fixture for 2 x F40T12 lamps per fixture online. You can get free shipping if you have a DoItBest store in your area. Now get yourself a Sasi ballast for an 8 foot T8 from ebay, $12 plus shipping, throw out the T12 ballast, and replace with the Sasi: it will overdrive your T8 lamp to make it give out the light of a T5, but at less than half price - and buy either an 850 or 865 series triphosphour T8 lamp - it will fit in the same fixture as for the T12, where the T5 will not. This has lots of blue, and all the spectrum you need for growing, plus they are CHEAP! Your full spectrum lamps are more expensive, but there is no added benefit for the cost. You will be getting 5000 lumens per T8 lamp, driven that way, with NO DANGERS - this method has been used for years with no problem. Make sure you are getting an EIGHT foot ballast to drive these four foot tubes - this technique is called overdriving. you can look it up on wikipedia, but in a nutshell, that is all there is to it. You must get the T12 fixture, because the 8 foot ballast is BIG, and needs the big case of the old F40T12 fixture! T8 fixtures are too tiny, and they have a tiny ballast, so that is the reason.

That's what I do, any questions, email ptmozarowski@hotmail.com - I don't make any money in this deal, just giving out the best advice for the money - Paul Moz.
Kthulu
Original Author
11 years ago
Other opinions?
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nick1427d
11 years ago
If you have a home depot or equivalent close, buy the 4ft t8 shop lights and buy 2 daylight bulbs. I've grown lettuce without any problems. In fact I usually direct sow the seed in a planter like one you'd put on a deck or below a window (plastic) and just grow them in that, works great. I've grown lettuce all year long with this setup. Get a timer and have the lights run for about 10 hours a day.