The consensus among the many experienced gardeners at GardenWeb is that ordinary 40-watt fluorescent bulbs, in standard "shoplight" type fixtures (inexpensive and widely available at home-improvement and general retail stores) are adequate for the home gardener starting seeds indoors.
Lights marketed as "growlights" or "plantlights" ,etc.,produce more red and blue light than regular fluorescents,but are often very expensive,sometimes downright exorbitant.
Many gardeners recommend using one "warm"(usually sold as "kitchen and bath" or "soft" lights,and having more of the red and/or blue wavelengths) and one "cool"(regular) bulb in each fixture to provide a "fuller spectrum" of light. An explanation of how plants use light may be useful here.
Light,whether from the sun or artificial sources,consists of varying wavelengths of radiant energy. In their normal state our eyes perceive these wavelengths together as "white light". Everyone is familiar with the spectrum of colors made visible when white light is refracted by water droplets to produce a rainbow.
Plants mainly use the red and blue wavelengths of light. Red is utilized in photosynthesis(how the plant produces it's food), blue influences the hormone systems that control growth.
It would seem that extra red and blue wavelengths in a light source would be beneficial, but in practice,at least in growing seedlings, intensity of light seems to be more important than spectrum. The much-higher cost of special "growlights" does not necessarily produce better seedlings!
The combination of a warm and cool bulb makes sense,but if cost is a factor(warm bulbs cost up to 3 times as much as regular tubes), standard fluorescents will work just fine.
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