HID lights for flowers/veggies

[Klaus Peper]

Sodium high pressure lamps have highest efficiency of 25%.
Their spectrum is narrow, the light appears yellow.
Metal halide lamps have 22% and have a wide spectrum, the 
light is the best white generated by any light source.

It appears that the spectrum is for the plant of minor 
importance. Professional growers mostly use sodium because 
of their efficiency.Amateurs prefer halide since they like 
more the natural outlook of their plants.

In most cases 450W lamps are used. Such a lamp will 
sufficiently cover 3m x 3m if 2m above ground, giving the 
plants all light they need.

I use 150W lamps both in my greenhouse 3m x 4m with good 
results (additional lighing), and in a 1m x 2m culture room 
in the basement for very good results.For glass vitrines a 
lamp 70W or 150W is great.

I experience with artificial lighting since 10 years, and 
it appears that halide lamps are far superior to any other 
light sources like fluorescent bulbs or "special plant" 
lamps with mercury.

70W halide lamps are commercially available as indoor 
illumination ( in Germany: Conrad Electronics), 450W lamps 
both halide and sodium are available for commercial 
greenhouses. 150W lamps can be build by yourself by 
modifying cheap 500W halogen flooders.

-- Klaus