To efficiency implement the introduction of greening base material on organic substrate mainly for a birch tree by mixing sludge conpost in the greening base material consists of main material containing organic material.

In a face of slope greening method where greening base material consisting of main material containing organic material is blown to the face to slope to form organic basement, sludge conpost is mixed in the greening base material to promote the growth of tree plants such as birch trees on the organic basement. As the sludge conpost contains useful bacteria, it is considered that the useful bacteria grows in the organic basement and the propagation of harmful sterilizations for tree plants to grow in the organic material is thus restrained. To obtain the growth promotion effect of tree plants, the sludge conpost is desirably mixed in the greening base material at a volume rate of 100-300 liters per 1m3 organic basement, before blown.