Lumen is the most important factor and criterion in the traditional grow light over the past decades,but now,to the LED grow light,Lumen is only one standard,PAR(Photosynthetic Active Radiation) value is far more significant than lumens.First,let’s have a look at some pictures of the plants chlorophyll(some land plants and some tropical freshwater plants) response to the light source,these pictures come from different research institutes.
Over the past some years,LED grow light users always pursued high lumens,and most of the LED grow light were built with 630nm and 460nm,for these two spectrum all have high lumens,but by looking the above pictures,we can see,plants chlorophyll actively response to 650-670nm,430-440nm.But,we all know,the closer to UV or IR spectrum,the lower lumen is,and the price of these LED chips are also more expensive than 630nm and 460nm.
We often hear users say:My LED grow light are built with high lumens,but the yield of my medical plants is not as good as I expect,for they have forgotten the PAR value,they have ignored what the plants really need.The 550nm green wavelength has the highest lumen to human eye sensitivity,but it also has the less effect to the plants.And a 42mil red 660nm LED chip is very close to the chlorophyll active response,input volt 3.4V,input current 700mA,only got 15-20 lumens,but the same elements of a 42mil 630nm LED chip got 70-80 lumens.
So,how to balance the lumens and the PAR value in your LED grow light can be the most significant standard while choosing the LED grow light.If you would like to build your grow light with high PAR value and a relatively high lumens,four spectrum to six spectrum are needed,430nm,460nm,630nm,660nm,some users also like 610nm and 2700K-3700K warmwhite.
We must understand,the LED grow light can be built with very pure spectrum,it is far more different from traditional grow light,if we only pursue the high lumens,we may ignore what the plants are really absorbing,and this will finally affect our yields.The LED grow light wavelength can be build very pure,it is really completely different from the conventional grow light,so we cannot use the old lumens criteria to build a LED grow light.