Cactus e Dintorni

Habitat: Mexico, Texas.
Description: globular, sometimes upright cylindrical, cacti with big areoles each of them bearing a central hooked spine; they may develop a taproot. The diurnal flowers are borne at the top. In their natural habitat, they have adapted to growing on slopes with chalky soil ranging in altitude from 200 to 2000 metres (650 to 6500 feet) approximately.
A synonym is Grandulicactus. Some botanists group them into the Sclerocactus genus which also includes some Hamatocactus.
Soil: mineral mix or otherwise a mixture of pumice, lava, sand and clay with a small amount of humus, pH of 7.5. Special care must be taken to avoid waterlogging: pour some gravel all around the taproot as well as the base of the stem since they’re prone to collar and root rot.
Location: full sun in a well ventilated site sheltered from rain.
Temperature: a minimum of 2-3° (36-37°F) is recommended.
Water: these cacti enjoy being frequently, or even daily, sprayed with water  from March through to October. Start watering when the mean night temperature is around 20°C (68°F) and stop at the beginning of autumn. Avoid waterlogging and excessive humidity. Do not water from mid-July to mid-August.
Cultivation tips: easy to raise from seed; better results are obtained with grafting. High humidity in the wintertime is most harmful.
Main species of Ancistrocactus: Ancistrocactus scheerii, delicate and very prone to rotting; the known forms are brevihamatus, megarhizus, tobuschii (grafting is recommended);
Ancistrocactus uncinatus, ssp. wrightii e crassihamatus (the least demanding) a glaucous plant with woolly areoles, each with a long central spine; prone to mildew, it prefers a location in full sun; water every 10 days during the warmer months. It can withstand a minimum temperature of -10°C (14°F). Synonyms are Echinocactus u., Grandulicactus u., Hamatocactus u.