Growth Efficacy - From Electricity to Plant Growth

1 minute read

Ida Fallstrom Plant and Light Expert from Heliospectra presents on the topic of Growth Efficacy from the International Symposium on Light in Horticulture. Learn more about how PPE (Photosynthetic Photon Efficacy) plays in the role of Plant Growth. Uncover why Far-Red light is not included in the calculation of efficacy. Also, learn about LED Lights Grow Lights that are optimized for plant growth with a Spectrum targeted for higher PPE.

View the Presentation on the Growth Efficacy-From Electricity to Plant Growth >>




Plants grow healthily and most efficiently under a balanced light spectrum. It is especially crucial to provide such lighting conditions to plants grown under sole-source LED lighting. Due to the photosynthetic photon efficacy (PPE) variation among LED elements in different colors, LED grow lights with a spectrum optimized for plant growth may not excel in PPE.  For example, far-red (FR) light (700-800 nm) has positive effects on plant development, architecture, and flowering as shown in numerous researches, but is not considered as photosynthetically active radiation thus not included in the PPE calculations. Therefore, it is in our interest to compare the overall growth efficacy (g/kWh) of LED grow lights with spectrum optimized for plant growth and that with spectrum targeted for higher  PPE.


  • By including far-red in the growth spectrum, the PPE is reduced.
  • Plants grown with FR spectrum were larger in size and had higher biomass than the ones grown under the “PAR” spectrum.
  • The growth efficacy in the crop was higher in the FR spectrum, even though the lower PPE.
  • These results indicated that the PPE of a grow light is not an accurate way of describing the performance of the spectrum.

Growth Efficacy