About

Pediocactus simpsonii, known by the common names mountain cactus, snowball cactus, and mountain ball cactus, is a relatively common cactus that has adapted to survive in cold and dry environments in high elevation areas of the western United States. It can be found at higher elevations than any other cactus in North America. While not a landscape dominating plant, it is a relatively common species and the most common member of the genus Pediocactus. Because of its beauty and adaptation to cold environments it is sometimes grown by gardeners in areas that have few other choices due to the limited number of cactuses with cold adaptations. Like many cactuses its populations are sometimes threatened by this desirability due to the theft or removal of plants from the wild by collectors.

How to grow it

The attractiveness of the "beautiful flowers" is noted even botanical texts and so mountain cactus is a plant desired by gardeners for use in rock gardens in cold climates. When grown in a garden setting the mountain cactus requires a loose soil that will not set too hard when it dries. Plants survive well with a growing medium that is two-thirds sand and one-third rotted leaves, with a layer of pure sand around the base of the plant. Rotting may occur if water remains around the plant. Flowering is reduced if mountain cactuses are not kept dry and cool during the winter season. Though very hardy in cold climates, these cactuses will die if transplanted to a hot desert climate.

Germination studies on mountain cactus seeds indicate some need of cold-moist stratification. Only 10% of seeds germinated at 21 °C after eight weeks where on the other hand 67% germinated at 4.5 °C in 17 days.

Where it grows

Pediocactus simpsonii is found throughout the interior western United States from Arizona and New Mexico in the south to Idaho and Montana in the north. It can also be found in Nevada, Utah, Wyoming, Colorado, and South Dakota. In Montana it is only found in the mountains in the southwest of the state near to the border with Idaho. It if found throughout much of the southern, non-panhandle, portions of Idaho, excluding only the western edge. In Wyoming it grows in the southern and the western sides of the state. In Nevada it is found in the mountain ranges of the Great Basin in the eastern side of the state. Utah's populations can be found through much of the state where suitable habitat is found. In Colorado it grows in the foothills, mountains, and west slope of the state. It is found only in a few isolated populations in northern Arizona and is likewise found only in the mountains of northern New Mexico.

Other Pediocactus plants

Pediocactus bradyi subsp. despainii · Marble Canyon cactus · Knowlton's miniature cactus · Simpson's Hedgehog Cactus · Kaibab pincushion cactus · Navajo pincushion cactus · Siler's Pincushion Cactus · Pediocactus bradyi subsp. winkleri · Pincushion cactus