Peat is widely used as a growing medium in greenhouse production, but heavy exploitation of peat will seriously destroy the ecological environment. It is necessary to find new material to substitute for peat. In this paper the buffering capacity of several substitutes growing media which made by composted agricultural cast-offs were studied. The results showed that the acid, alkaline and saline buffering capacity of the substitute media were better than the peat and the non-organic media. The substitute media, therefore, have better synthetic characteristics than the peat, which ensures a balanced environment for the root system.