Foliar feeding is a method of applying fertilizer and nutrients by spraying onto the leaves rather than putting into the soil or water to be absorbed by the roots. The process has been the subject of a number studies, prompting many growers to use it in their growing programs.
Although foliar feeding is never an alternative to building up healthy soil, there are some cases where foliar feeding is quite beneficial. Spraying directly onto the leaves is a fast way to supply nutrients. If your crops are under stress from drought, pest-attack or disease, it's definitely worth spraying them to speed the recovery process. An ailing plant can improve its form visibly after spraying .
When spraying your plants, be sure not to let any of the spray near your LED grow lights. The fans of the LEDs will pull the spray inside and damage the lights. Not only is the liquid not good for the LED grow light, or any other electrical device for that matter, but the chemicals in the spray will react with the electronic components and surely damage your light.