Definition - What does Micronutrients mean?
In cannabis cultivation, micronutrients refers to the six plant nutrients that the marijuana plants require in much smaller doses (quantities) than macronutrients.
In doesn't matter what strain of cannabis one is growing, all types of cannabis require minor amounts of the following micronutrients: chlorine, molybdenum, copper, iron, manganese, zinc, and boron.
Hydrolife explains Micronutrients
In addition to micronutrients, plants require macronutrients (primary nutrients) and secondary nutrients. Unlike primary and secondary nutrients, the plants require the micronutrients in minuscule amounts.
Because plants require so little micronutrients, it's rare for cannabis plants in their seedling and propagation stages to be deficient in any of those elements listed above. This is because most plant nutrients purchased from the store contain trace amounts of these nutrients, or else they are already found in the soil in which your plants are growing.
To determine whether your plants indeed require micronutrients, cultivators must first try to determine if the symptoms their plants are showing is related to other issues such as insects, droughts, overwatering, or overfertilizing. It's sometimes possible to test your plants by getting a soil analysis or plant tissue analysis done.
If the plants are found to lack one or more of the six essential nutrients, they are administered small doses of micronutrients at a time. This can be done either through an all-purpose fertilizer, or a tailored nutrient recipe you find or buy. For adding micronutrients, many growers decide to add organic inputs like kelp, molasses, bat guano, or vermicompost (worm castings) to their plants, as these ingredients are all rich in micronutrients.