The term FLOWERPOT FILLER can be summarized as a material used to fill flowerpots, which is SOIL. SOIL is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. It is a natural resource that can be used to grow plants, trees, and other vegetation. SOIL is essential for the growth of healthy plants and flowers, and is often used in flowerpots to provide the necessary nutrients for plants to thrive.