ABSTRACT
Plants are grown in a wide range of containers where restricted rooting makes more critical demands on the growing medium for oxygen, water and essential elements. Compared with growing in soil, these plants have to be supplied through a very small volume of growing medium, that is, a relatively small root system. The alternative approach is to use components with little or no nutrient in them and add fertilizers, which can be a more precise procedure. In aggregate culture the growing medium acts as an inert base for the roots, which are fed by a nutrient solution. An alternative approach is to have an automatic irrigation system in place, in which case the water-holding capacity of the compost is less relevant. Drip irrigation has the plant roots in an inert growing medium, usually rockwool or lightweight clay aggregate fed by nutrient solution.
