hydroponics grow light

What light do plants really absorb? In the 1970s a scientist called McCree determined the wavelengths of light a plant can absorb. He assessed the relative quantum efficiency of different wavelengths of light on photosynthesis. In other words he recorded the rate of growth of plants exposed to each wavelength or colour of light. McCree discovered that plants use all parts of the PAR spectrum but at different rates. The quantum efficiency for red is close to 100% efficient whereas blue and green were less efficient, ranging from 65% to 75%. McCrees action spectrum identifies what colors of the visible spectrum are best for photosynthesis. McCrees action spectrum is the correct reference for assessing the suitability and effectiveness of a grow lights spectrum output. Blue Light Blue lights with a Kelvin color temperature from 5000K to 6500K or wavelength in the 400-500 nanometer range are best for the vegetative stage of the grow cycle and for starting seeds indoors. This color range...

Ceramic Metal Halide Grow Lights CMH lights were introduced in the 1980s, but with recent discoveries in horticulture research, it makes sense why many growers are utilizing this technology.The CRI of CMH's is around 90-92, close to the spectrum you get from the sun .The claim from CMH lovers is that your plants can enjoy a nearly full spectrum white light, very similar to natural sunlight that lasts longer than your HID counterpart. A CMH's Color Rendering Index (CRI) rating is pretty close to the sun. CRI is a measurement of how true colors stay when the light is set upon them.  HPS grow lights  are 20 - 30 (that's why it's all orange/yellow in your grow room during flowering) while Metal Halides are 60 - 65 (which is why there's a little bit of a blue tint in your growing area when you're vegging).  CMH grow lights  come in with a CRI rating of 90 - 92 making them only 8 points off from our most natural source of light. Right off the bat, once you turn on ...