PURPOSE: To obtain the seedling bed not causing the pollution of environment, excellent in its water-holding property and in its heat-insulating property, and useful in the fields of agriculture. etc., by kneading a pulp, etc., with a decomposition type foaming agent and water, adding plant seeds to the mixture, molding the mixture, thermally foaming the molded product, and subsequently drying the foamed product.

CONSTITUTION: The production of this seedling bed comprises kneading a pulp, a bio-degradable thickening agent such as sodium alginate preferably in an amount of 0.5-20 pts.wt. (per 100 pts.wt. of the pulp), a decomposable foaming agent such as sodium bicarbonate preferably in an amount of 10-20 pts.wt., and water, further adding plant seeds, molding the mixture, thermally foaming the molded product, and subsequently drying the foamed product.