LED grow lights have made waves in the grow community in the last 20 years, surpassing HPS lights in efficiency (lumens per watt). This means your electricity bill will be much lower when using LED lighting.
However, HPS lights are cheaper to buy initially than their LED equivalents. So which one makes most sense for growing?
We know that plants absorb light in the following range:
Basically red and blue light are the main absorption peaks of most plants and photosynthetic organisms.
Looking at an analysis of a leading HPS grow light we see the following spectrum:
The red and blue light essential for plant growth is not pronounced in HPS lights. Worse yet, most of the light falls within the green/yellow wavelengths, which is simply reflected and not used by a plant.
Looking at the analysis of our LED grow light we see:
With LED lighting, we are able to pick and choose a very specific spectrum of light, allowing for optimisation. LED lights can be any wavelength you like for the purpose of light therapy, or for grow lights – the exact spectrum that plants like.
While LED lighting might cost more initially, it pays for itself quickly with lower electricity costs, and better yields on plants.
Most of the world’s infrastructure is being upgraded to LED lighting at the moment. All modern industrial scale indoor vegetable growing operations now use LED lighting because it maximises profits.
At this point in history it is time to retire HPS lights to the museum of indoor growing.