2nd Year Maturity. Pampas grass is one of the most popular ornamental grows in the entire world. Seeds mature to enormous 6-10' tall grassy tussocks with bushy, feathered tips. Pampas grass is native to the plains of South America and thrives in a variety of dry and arid climates. Pampas seeds have been a favorite perennial grow for many residential, commercial, and rural spaces. 1000 seeds.