Light + Science: The FGI Grow Lighting Story

Plants need a different spectrum of lights than humans do. In the 1970’s Dr. Keith McCree developed the plant response curve to illustrate how plants absorb light, or what their photosynthetic response as a function of light energy. Plants respond to the light spectrum in different ways and at different times in the growth phase.

McCree Action Response Curve

spectrum wavelength

In working with lighting for plants, it’s important to target the correct wavelength, as well as intensity of light. Cannabis, for example, thrives in the vegetative stage using the blue light spectrums and can produce healthy flowers using the red end of the spectrum.  The green spectrum in the center is absorbed at less than 15% by plants, so it’s function is mainly targeted to the human eye although as you can see on the McCree curve, there is some benefit inside that spectrum.

spectrum wavelength study

Forever Green Indoors puts the science in LED grow lighting for cannabis. Over the years we’ve heard many growers say LED’s don’t work well for growing marijuana. On the flip side, we asked them what does work and learned a lot about HPS, CMH and Florescent lighting. Most growers also agree the sun is the ultimate grow light so we studied that as well.

spectral analysis the sun

When growers decided to start trying to grow plants indoors, there were very few choices for lighting that would provide enough intensity to initiate the photosynthetic plant response as well as the sun does. The best option for the intensity needed ended up being warehouse and parking lot lighting. 1000W lamps that could give the plants what they need. The downside? Very high-energy usage and a lot of heat output that had to be then drawn off the plants to keep them healthy.

spectral analysis gavita 1000W
spectral analysis t5 ho fluorescent


The lack of heat management as well as high-energy bills drives the need for LED energy efficient lighting. The side benefit of technology advances, however, is that LEDs can be controlled. The diodes can be chosen based on what the grower’s needs are, and what the plant’s needs are. Both in the growth phases and also in space planning for facilities. Growers wanting to maximize yield can grow with vertically stacked shelves using LED because of the heat management. Growers that want to control what is happening with plants in different stages of growth can choose spectrums that are designed just for that phase of growth.

FGI grow test Example 1
FGI Grow Test Example 2
FGI Grow Test Example 3

We’ve built our lineup of LED lamps to mimic the spectrum and light intensity of not just the sun, but also of HPS, CMH and fluorescent lighting. Our research paid off. We have bloom/flower lights that include the same spectrum you find in HPS lights. Our Veg lamps include the same spectrum found in CMH and our clone/veg lights include the favored spectrum from fluorescent lighting.  In addition our lamps include spectral colors that the sun produces which are not found in HPS, CMH and Fluorescent.

Our bloom spectrum not only matches HPS but also adds important wavelength peaks that the HPS lights are missing 

FGI lightpanel spectral analysis 500 & 700

Lightpanel series vs Gavita 1000W HPS

Our clone & veg spectrum not only matches T5HO but also adds important wavelength peaks that the other lights are missing

FGI Lightbar Series Spectral Analysis

FGI Lightbar vs. T5HO Fluorescent

Test grows across the northwest have proven that our approach not only works but achieves results that can increase your profitability.


  • Higher plant yields
  • Improved THC levels
  • Excellent terpene profiles
  • Up to 50% energy savings
  • Long lamp life with little degradation: consistent crops
  • Maintenance free
  • Energy savings in heat management
  • Equipment asset that increases the value of your business
  • Qualifies for utility rebates
  • ROI of less than 2 years
FGI Case Study