The present invention relates to a potting soil, comprising a phosphate containing fertilizer, in which at least a part of the phosphate is present as polyphosphate. The invention also relates to the use of a phosphate containing fertilizer, comprising a polyphosphate, and if desired, at least one nutrient selected from the group of nitrogen containing nutrients, potassium containing nutrients, magnesium containing nutrients and trace elements as basic fertilizer for a plant in potting soil.