The invention relates to the field of seed germination and growing of plants. A composition comprising a clay, an inert material, optionally a fibrous material, and a fourth component is provided, characterized in that said fourth component comprises a cation selected from the group consisting of Al, Zr and Ti and an anion selected from the group consisting of oxyhydroxide, oxychloride, nitrate, sulfate, chloride, hydroxide and alkoxide, and wherein the concentration of said fourth component ranges from 0.1 to 70 percent by weight (w %), preferably 0.5-25 w %, more preferably 1-10 w %, of the total weight of the clay, the inert material, and optionally the fibrous material, together.