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The mountain cactus, or Pediocactus simpsonii, is native to the dry mountain regions of the Pacific Northwest. It generally prefers cooler temperatures, and usually requires little water throughout much of the year, though it does have increased water needs during its late winter, early spring and autumnal growth periods. The mountain cactus may produce either pink or yellow flowers and reddish-brown fruits. These small perennial plants can be difficult to propagate from seed, and are usually best propagated by grafting onto other species.
This particular variety of cactus is native to higher elevations and prefers cooler temperatures than some other species. They are most often found at elevations ranging between 6,000 and 10,000 feet (1,800 to 3,000 m). They seem to prefer rocky ridges and dry mountain valley habitats. They typically experience growth periods during late winter and early spring, as well as in the autumn. While these cacti require little water throughout the rest of the year, they generally need regular water during their growth periods.
This plant is also sometimes known as the hedgehog cactus or mountain cactus. It may be 3 to 8 inches (7.6 to 20.3 cm) tall. It may produce single stems, or small clusters of stems. Stems are typically oblong or round, and may be 3 to 5 inches (7.6 to 12.7 cm). Spines usually grow in clusters of eight to 12, and are typically white in color. Spines may be dark brown to black at the tips.
The mountain cactus may produce yellow or pink blooms. Some experts believe that the color of the blooms on wild plants changes depending on whether the plants are found on westerly or easterly slopes. Blooms are usually pale in color and may only be 0.6 to 1 inch (1.5 to 2.5 cm) in diameter. They typically appear in late spring and last through the early summer.
Though generally quite cold-resistant, these cacti often go dormant during the coldest winter months, and may die back to the ground's surface. In general, these cacti require a minimum average temperature of 50 degrees F (10 degrees C). They usually prefer partial shade and dry, rocky soil conditions. These plants may produce round fruits, which are often green in color when immature, and tan or reddish-brown in color when mature. The fruits of the mountain cactus often split open to release their seeds when they are ripe.
The mountain cactus can be difficult to propagate from seed. Germination can be a long, complicated process and the resulting seedlings are often too weak to survive. Gardeners are often encouraged to graft the mountain cactus onto hardier species for ease of propagation.