PURPOSE: To permit the mixed plantation of trees and western lawn by installing a seedbed onto a net and charging the seeds of trees and flowers and fertilizers into the seedbed and installing a cover sheet for preventing the mixing of the seeds of western lawn into the seedbed, onto the surface of the seedbed.

CONSTITUTION: A seedbed 2 is formed by keeping the seeds 4 of trees or flowers, a lately effective fertilizer 14, and a soil improving material or water holding material 5 between an upper paper 13 and a lower paper 12, and a cover sheet 3 installed onto a demountable net 8 is applied onto the seedbed 2. After a net 1 is fitted into a cut-in groove formed on the seedbed 2, a seedbed holding tape 11 is wound onto the seedbed 2, which is fixed onto the net 1, and a seed spraying net equipped with the seedbed is formed. The net is unfolded onto a normal plane 7, and fixed by anchors, and then seed spraying of western lawn is executed, and then the net 8 and the cover sheet 3 are removed.