Garden & Greenhouse October 2017 Issue - Page 30

FEATURESTORY by Eric Hopper Maximizing Lighting Efficiency O f the many variables which affect plant growth in an indoor garden or green- house, none are as influential as the ar- tificial light source. The artificial lighting system is literally the sole energy source for an indoor garden and without light energy photosynthesis is impossible. It is important for horticulturists to re- member that each indoor garden has a limited amount of light energy. To maximize his or her return on in- vestment and to make an indoor garden as efficient as possible, an indoor horticulturist must make the most of his or her given light energy. When I was a hydroponic retail store manager, growers constantly asked me how they could increase their yields. My answer was always “maximize the effi- ciency of your light source”. In other words, to get the most out of an indoor garden, a grower must know the basics of light energy, how it relates to indoor hor- ticulture, and how to maximize its efficiency. Light Energy The inverse square law states that light energy diminishes exponentially as it travels away from its source. Light energy is emitted evenly and in all direc- tions from one point. As the light travels and spreads, the intensity diminishes. The most important detail for indoor growers to remember is that light intensity is directly related to the distance from the light source. Plants grown outdoors under the sun are seemingly unaffected by this phenomenon because, after travel- ing all the way from the sun to the earth, the distance from the top of the plant to the bottom is quite insig- nificant. Plants grown indoors, however, are extremely susceptible to the inverse square law because the (Continued on page 34) 30 October 2017