> Organic Gardening said if you have a double tube flourescent light holder,
> to use one cool white and one warm white light. this will cover the whole
> spectrum.Chlorophyll has two absorption maxima - one red at around 700 nm
and one blue around 440 nm, which means that much of the energy
radiated by full-spectrum flourescent light tubes is wasted.
These tubes are intended for human eyes, which have a maximum
sensitivity around 550 nm, which is yellow light. Special lights
are available from fluorescent light suppliers. Osram has a type
called L-77 which I have tried, costs about the same as ordinary
fluorescent lights. In the States, I think Osram may be known
as Silvana, but I am not sure.
Hope this helps.