Cactus e Dintorni

Habitat: California, Arizona, Nevada, Utah, New Mexico, Colorado.
Description: a genus of globular or cylindrical, usually small and solitary cacti. The stem is marked by 12 - 20 ribs and bears bell-shaped, diurnal flowers in the summer. In the wild, they grow between 500 and 2500 metres of altitude (1600-8200 ft). They may be synonymous with some species in Echinocatus, Pediocactus and Toumeya.
Soil: 50% sand, 25% good garden soil, 25% pumice stone 1-3 mm (0.04-0.12 in) in diameter.
Location: grow in filtered light.
Temperature: they tolerate low temperature (down to -7°C/19°F) as long as the soil is dry.
Water: water abundantly when growth restarts (in February); occasionally during the summer and winter rest periods.
Cultivation tips: even when dormant, they need plenty of ventilation so they’re not suitable for a greenhouse; they’re best grown outdoors sheltered from excessive rain. They awaken early and go to flower from March to May; growth reaches its peak in May and June,  then they re-enter a period of rest in July-August, wake up again for a short time in September-October and finally stop growing when winter is about to begin. They are sometimes grafted.
Same treatment as the genera Pediocactus, Austrocactus, Toumeya, Echinomastus.
Main species of Sclerocactus: Sclerocactus brevispinus; Sclerocactus glaucus; Sclerocactus cloveriae;
Sclerocactus mesae-verdae; Sclerocactus parviflorus; Sclerocactus papyracanthus; Sclerocactus polyancistrus;
Sclerocactus pubispinus; Sclerocactus spinosior; Sclerocactus schleseri; Sclerocactus whipplei; Sclerocactus wrightiae; S. wetlandicus.