Carnegiea gigantea is a cactus endemic in the Sonora desert, in the adjacent areas in southern Arizona and Mexico.
Carnagiea gigantea, also known as “Seguaro”, grows a columnar, little ramified stem. This is thorny, fleshy and slow-growing, and can get up to 13 m high and 3 m wide. It produces creamy-white flowes with a dense group of yellow stamens.
Saguaro is really slow-growing, and its roots need plenty of space. It needs repotting every year, in a well draining soil mix. Water regularly during summer, letting the soil get dry before watering again; during winter keep it dry. It is not cold hardy, so you absolutely have to avoid freezing temperatures. Young plants should be put in light shade, then they will need full sun.
Propagation can be done both by cuttings and by seeds. During spring, let the stem cuttings get dry and put them in fresh, moist cactus mix soil. Keep it wet until they root. Propagation by seeds is even easier: sow them in a well-draining substratum, and they will germinate in 2-3 weeks at 20°C.
Saguaro is probably the most famous cactus worldwide.