Gymnocalycium spegazzinii is a solitary, slowly growing cactus, densely covered with incredibly strong twisted spines pointing side wards and downward. The stems are flatten brownish-grey to almost black up to 18 cm (or more) in diameter.
The flower are open petaled, funnel-shaped, about 4(-7) cm in diameter, 3(-5) cm tall and white-rose in colour.
Gymnocalycium tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer. The soil is usually a rich sandy loam. Rains are frequent during the summer.
Needs moderate to copious waterings in summer, but do not overwater. Feed with a high potassium fertilizer in summer.
It is an excellent plant for garden rockery settings, desert type landscapes, patios and botanical gardens