PROBLEM TO BE SOLVED: To provide: a method for promoting and suppressing growth of a tree and a method for promoting flower budding and fruition of a tree and root crops, using diatomous earth or the like which allow the growth of the tree to be controlled, by burying or laying diatomous earth or the like; and a method for alleviating an adverse effect component's effect which reduces salinity concentration in the earth, by spraying or burying diatomous earth or the like to or into the earth.SOLUTION: Diatomaceous earth and the other component is laid, to promote growth of a seedling by covering diatomaceous earth and the other components with the earth, or to suppress the growth by exposing diatomaceous earth and the other components, such that the moisture amount in the earth is kept in constant, thereby allowing the growth to be controlled. Further, to an adult tree and root crops, the effects of moisture retention, fertilizer retention, and heat retention by diatomaceous earth and the other components can
