Echinopsis spachiana

Common name: Golden Torch Cereus
Synonym: Trichocereus spachianus, Cereus spachianus, Echinocereus spachianus, Cereus santiaguensis, Echinopsis santiaguensis, Trichocereus santiaguensis
Family: Cactaceae
Exposure: Best in full sun or light shade exposure
Temperature: minimum avg. 50 degrees F (10 degrees C)
Frost Tolerance:  Fairly cold tolerant, it can easy tolerate light frost
Watering: moderate water
Origin: Western Argentina, Bolivia

Description
Habit: Multi-stemmed columnar cactus, basally branching, 2 to 2.5 inches in diameter (5-6 cm), 7 feet tall (2 m); 10 to 15 ribs; yellowish areoles turning grey as they age; 1 to 3 yellowish centrals, 0.5 inch long (12 mm); 8 to 10 radials, 0.5 inch long (12 mm).
Stem: Stem upright, at first simple, later profusely branching at the base; branches ascending parallel with the main stem.  Up to about 2 mt, but usually smaller, 5 to 6 cm. in diameter, columnar; ribs 10 to 15, obtuse, rounded;
Areoles: About 1 cm. apart, large, covered with curly yellow wool, turning white or grey as they age;
Spines: Radial spines 8 to 10,  6 mm to 1 cm. long, spreading, stiff, sharp, amber-yellow to brown ;central 1 to 3 yellowish centrals, 12 mm long, stronger and longer than the radials; all the spines later becoming grey.
Flowers: Large white nocturnal flowers in late spring. The flowers are up to 8 inches long (20 cm), 6 inches in diameter (15 cm).

Care and cultivation
The growing and resting seasons for Echinopsis are the same as for Echinocactus. Research by J. Smith (former Curator at the Royal Botanic Gardens, Kew) showed that species like the Chilean Echinopsis cristata and its Mexican relatives thrive if potted in light loam, with a little leaf mould and a few nodules of limestone. The limestone keeps the soil open; it is important that the soil should be well drained. In winter, water must be given very sparingly, and the atmosphere should be dry; the temperature need not exceed 10 degrees C during the night, and in very cold weather it may be allowed to fall to 5 degrees C, provided a higher temperature of 14 degrees C is maintained during the day. In spring, the plants should receive the full influence of the increasing warmth of the sun; and during hot weather, they will be benefited by frequent spraying overhead, which should be done in the evening. The soil should never be saturated, as the soft fibrous roots will rot if kept wet for any length of time.

None of the species need to be grafted to grow freely and remain healthy, as the stems are all robust enough and of sufficient size to take care of themselves. The only danger is in keeping the plants too moist in winter, for although a little water now and again keeps the stems fresh and green, it deprives them of that rest which is essential to the development of their large, beautiful flowers in summer.

Propagation
easily from cuttings