Echinocactus grusonii

Echinocactus grusonii is a species of Echinocactus. It's type locality is Mexico.

Background
Echinocactus grusonii belongs to the small genus Echinocactus, which together with the related genus Ferocactus, are commonly referred to as barrel cacti.

While sometimes referred to as Golden Ball, this species is not to be confused with Notocactus leninghausii which have fuzzy, harmless spines and are native to Brazil and Paraguay.

Despite being one of the most popular cacti in cultivation, it is rare and critically endangered in the wild.

Growing as a large roughly spherical globe, it may eventually reach over a metre in height after many years. There may be up to 35 pronounced ribs in mature plants, though they are not evident in young plants, which may have a knobbly appearance. Note: Younger Golden Barrels do not look similar to the mature ones. The sharp spines are long, straight or slightly curved, and various shades of yellow or, occasionally, white. Small yellow flowers appear in summer around the crown of the plant, but only after twenty years or so.

Cultivation
Widely cultivated in warmer climates around the world, it is considered easy to grow and relatively fast growing. It has been increasingly used as an architectural plant in garden design. Jamie Durie, one of Australia's leading garden designers, has called it one of his personal favourite plants. A white-spined form is also in cultivation, as is a short-spined form.

While easy to grow, these plants do have some basic requirements; an average minimum winter temperature of 12°C (53.6ºF), good drainage with less watering in winter. Excess water in cool periods may lead to rot. Golden Barrels are hardy to about 15ºF (-8ºC) for brief periods.

Outside Mexico, Echinocactus grusonii specimens may be seen in collections of desert plants in many botanical gardens.