T. bicolor is native to Mexico Northeast and Texas. This cactus is widespread in the desert of Chihuahua where it grows in calcareous and stony soils and can live up to 2000 m of altitude.
T. bicolor is a cactus belonging to the Cactaceae botanical family. The plant is usually solitary but can grow in clumps. The stem is columnar, erect and can reach up to 15 cm in height and 10 cm in diameter. The stem is arranged in 8-12 ribs made of tiny tubercles covered with circular and hairy areoles. Areoles are woolly and bear from 9 to 18 red to yellowish spines, up to 3 cm long. Blooming appears in late spring early summer, and blossom are borne at the apex of the stem. The showy ephemeral flowers are funnel-shaped, pink to magenta and can reach 10 cm in diameter. The flowers open in the afternoon sun and die a few hours later. Fruits are green to dark red and covered with flakes.
This is a slow growing cactus, easy to cultivate. The plant needs a full light sun exposure but is recommended to avoid direct sun-light in the hottest periods. The plant does not like temperatures below 5°C so it needs to be placed indoors in the coldest periods. The soil should be mixed with pumice, clay and loam to allow the drainage and prevent the root rot, the plant is prone to it indeed. Remember to use a perforating pot to drain excess water. Watering can be done regularly in Spring and Summer: during the vegetative period you can water the plant (every 7 days), checking that the soil is completely dry before watering again; in winter you should stop the watering to allow the plant to enter dormancy. If you want a faster and lush growth you can fertilize the plant once a month during the growing season with the specific fertilizers for cacti; stop fertilizing throughout the winter. If the pot starts to be too small for the plant you can repot the plant in a pot 2 cm wider. Repotting should be done early in the growing season with fresh new potting soil. Be careful to red spiders and mealy bugs.
The easiest and fastest method of propagation is by seed but is also possible to propagate the plant by cuttings. By seed it is very simple to propagate the plant, it is enough to sow the seed in a sandy loam soil and keep it with a high level of humidity and at temperature of 14 C°.
The name comes from the Greek “thele”, that means nipples, and refers to the many tubercles that furrow its surface (an origin of the name similar to that of the genus “mammillaria”). The name “bicolor” refers to the double color of the spines.
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