Ferocactus haematacanthus is a solitary cactus with initially bluish-green, later green stems, growing up to 30- tall and 25- in diameter. The stems have 13-17 ribs and bear reddish thorns. Adult plants have merged areoles. The red spines consist of four central spinesmeasuring long and six to seven marginal spines measuring long. The cactus produces funnel-shaped, purple-pink to rose-purple flowers measuring 6- in length and diameter, followed by egg-shaped, deep purple fruits that are 2- long.