Chemical properties exert a considerable influence on the behavior of growing media, particularly in regulating the composition of the nutrient solution. This effect depends on the nature of components: mineral growing media are chemically inert and weakly affect the nutrient solution only in the first days of cultivation. Organic growing media constantly release and immobilize elements, playing a key role in controlling plant availability of nutrient and toxic ions. The most important chemical characteristics of growing media are cation exchange capacity (CEC), salinity, and acidity. These can be changed using amendments. The chapter examines these chemical properties of growing media and growing media components, describes how they can influence soilless cultivation and analyzes latest trends in their management. Finally, a case study on the modification of pH, salinity and nutrient content during storage of two growing media is reported.