What can I grow under a T5 Hydrofarm 4' x 4 bulb light fixture?

[jeremyinsf]

My lighting store in SF basically told me the same thing. I'd need a Spectrometer or PAR to get actual useful info. It's in part why grow bulbs get replaced even when they "look" fine. They just aren't giving out the same (true) energy any longer. And a basic light meter doesn't detect that.

[naoki]

Originally Posted by rosemadder

Ooh! Highly intriguing! Do you know of any good sites that explain a bit more about that sort of thing? If I recall correctly, PAR meters are rather pricey, so I may not be able to get one for a long while yet, but I'd like to research this in the meantime.

Here is a rough calculation comparing florescent light vs sun light:

http://www.orchidboard.com/community...tml#post514860

I don't know how valid the number listed in the AOS article, but 15 hours of 1200fc florescent light is roughly similar to 1200-1800fc peak sun light in this calculation.

[DTEguy]

Rosemadder: Sorry, I don't know any good website on PAR analysis. However, here's an article on light intensity equivalent for constant light if you haven't seen it.

http://www.aos.org/default.aspx?id=516

Not sure how useful it is since we don't really know our PAR.