I'm speaking from no expertise or specific knowledge here (which occasionally does stop me from
responding), but I believe you're referring to UVA and UVB which are merely different wavelengths in
the UV spectrum, and are essentially unused by plants.

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Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

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"Al" wrote in message ...
I understand there are two kind of UV light, like cholesterol; a good one
and a bad one.

Is anybody out there that can explain UV light with regard to transmission
through glass and plastic, plant requirements of the stuff and how they use
it and if those UV light blocking windows are good or bad.

I know in general it affects color quality and perception, pigment fading,
greenhouse plastic decay rates...