Indoor horticulture adopted HPS and MH (HID) type lights a long time ago because they were the only systems that delivered a high enough level of PAR light. Even though HID lights were developed for outdoor street lighting applications, they delivered good results when used for indoor growing. However, HID lights suffer from a few drawbacks. First they are not the most efficient at delivering PAR light and thus lose most of their energy as heat rather than useful light for plants. This results in huge energy bills as well as the need for supplemental cooling of the lights with fans and ducting. Florescent lights do a good job for vegetative growth but are not powerful enough for flowering. These traditional types of grow lights cannot be designed to deliver the specific light wavelengths that plants absorb the most. LEDs are much more efficient and create much less heat to generate high intensity light for indoor growing and therefore do not require supplemental cooling. Also, LED technology makes it possible to select only the light frequencies most absorbed by the plants further reducing energy waste and improving growing results.