There are undoubtedly many benefits to growing with LEDs, including significant energy savings, spectral tunability, reduced heat, low maintenance and long lifetimes. However, converting to LED technology is a big investment, so growers should be sure to do their homework in advance. An incremental cost of four to five times that of HPS, means you have to look at many factors to determine if the ROI on converting to LED makes sense. Growers should consider not only the initial capital expenditure costs of the luminaires themselves, but also the incremental costs associated with a transition to LED lighting.  Growers in northern climates, for example, will have to compensate for the loss of heat from the traditional light sources in the winter—so the additional heating costs should be factored into the ROI calculation. A good way to get a true comparison between the cost of LED versus traditional lighting is to look at the cost per µmol delivered, as the outputs can differ from one product to another.