The Visible Light Spectrum
The first step to understanding grow lights is the electromagnetic spectrum.
Two measurements to know are Kelvin and nanometers.
Today’s LED grow lights typically have a Kelvin range of 2,700 to 6,500.
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Bulbs on the lower end of the Kelvin spectrum are better suited to promote flowering and fruiting.
Nanometers measure the specific wavelengths of specific colored lights.This includes wavelengths from about 380 to 750 nanometers.
As you might imagine, the visible light spectrum is also what drives organism growth and photosynthesis.
Each key in of light supports plant growth and development in a unique way.
On the other hand, blue light is responsible for chlorophyll production, root growth, and leaf thickness.
However, for most small-scale, residential applications (like houseplants), this kind of thing isnt necessary.
A grow light that provides the entire PAR spectrum is ideal.
Not only is it more cost-effective than other kinds of grow lights,LED lightsare also the most energy-efficient.
Plus, they are widely available.
The ideal value for indoor plant growth will fall in the 500 to 700 mol/m2 range.
However, if you dont see this value reported dont be alarmed.
How Long Should Grow Lights Be On?
On average, most plants benefit from the grow light being on for 8 to 10 hours a day.
Fruiting plants, for example, may need up to 18 hours of light per day.
Seedlings need 6 hours of darkness while more mature plants need 8 to 10 hours.
