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
For watering cacti, the golden rule is to make sure the soil is completely dry before watering! This will stop the roots from rotting. It is advised to always use a pot with a drainage hole so that excess water can get drained out. If kept in a sunny area, you will need to water it once every week. If it is in a semi shaded or filtered light area, you might need to water it once in 2 weeks.
Cacti like soil that is well aerated and fast draining. You can fertilise the cactus in the summer months when it is in its growing season. During the winters it is best to cut back on any fertiliser and let the plant rest.