Poa costiniana, also known as bog snow-grass and prickly snow-grass, is a species of grass in the genus Poa. It is an tussock-forming alpine snow grass that is widespread in high-elevation environments, where it is especially common in damp habitats and may form dense, nearly pure swards. The species was discovered by Joyce Winifred Vickery.
Poa costiniana grows up to high. It has leaf blades wide and long, mostly smooth, and rather rigid. The inflorescences are long. Flowering occurs in summer.
Poa costiniana is native to Northern Territory, South Australia, and Victoria. It is local to Mt. Kosciusko, with an average elevation of .