Plants need light. But what kind?
The best thing for any plant is natural sunlight.
As this is not available when cultivating indoors,
we require a worthy replacement.
The important factors for plant lighting are the output level (watts) of the ballast/lamp, and the light colour spectrum or the colour temperature (°Kelvin).
For example, a 250W lamp won’'t generate as much growth
as a 400W lamp, and a lamp that is closer to the light spectrum of natural daylight (approx. 6500°K), will enable much more natural growth than a very “warm” lamp (e.g. 2500°K).
On the other hand, you can use the colour temperature
to control the plant growth in a targeted way. For example, a higher red content in the light stimulates flowering and fruit formation for many species, and a higher blue content will encourage leaf growth.