Microbial is used to stimulate a plant's inbuilt immune system, thus improving overall plant health and increased resistance to attacks from pests and diseases.

With soil based horticulture many of the bacteria present are beneficial to plants in terms of breaking down organic matter and enabling the mineral elements contained within to be readily absorbed by the plant. In a hydroponic environment these beneficial bacteria are not present; therefore the potential for problem airborne or soil borne micro-organisms attacking hydroponic crops is very high.