Pediocactus simpsonii
mountain ball cactus
Overview
Pediocactus simpsonii is a small, globe-shaped cactus in the family Cactaceae, forming a single ball or a low cluster of stems 2-6 inches (5-15 cm) tall and wide, occasionally reaching 12 inches (30 cm) across in old clumps. The stem surface is divided into spiraling tubercles, each tipped with a cluster of 5-11 stout central spines surrounded by 15-35 shorter, paler radial spines. In spring the crown bears short, funnel-shaped flowers 0.5-1 inch (1.5-2.5 cm) across, ranging from pink and magenta to yellowish or greenish-white depending on the population. The fruit is a small, dry, greenish capsule. Native to cold high country, this cactus withstands hard freezes and snow cover, shrinking and flattening against the ground in winter to survive. One limitation in cultivation is its intolerance of summer moisture and rich soil, which readily cause rot in this slow-growing species.
Native Range
Pediocactus simpsonii is native to the interior western United States, ranging across the Great Basin and Rocky Mountain region from Washington and Oregon east to Colorado and south to New Mexico. It grows on dry, rocky slopes, sagebrush flats, and pinyon-juniper and montane grassland, at elevations up to about 11,000 feet (3,400 m).Suggested Uses
This species is grown by collectors in trough gardens, rock gardens, and gravel beds, and in alpine houses where winter wet can be controlled. Its spring flowers draw native bees. As a cold-hardy ball cactus it is studied as an example of high-elevation Pediocactus spp..How to Identify
Appearance
Size & Dimensions
Height2" - 6"
Width/Spread2" - 1'
Bloom Information
Flowering occurs in spring, often April through June, soon after snowmelt as the plant swells with moisture. The short flowers open at the crown for a few days each. Bloom timing shifts later with higher elevation.
Detailed Descriptions
Flower Description
pink to magenta or greenish-whiteFoliage Description
green stemGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Pediocactus simpsonii grows in full sun and requires very sharply drained, gritty or rocky mineral soil that stays dry, especially in summer. It tolerates winter temperatures far below freezing when kept dry, withstanding hard frost and snow cover that few other cacti endure, yet summer rain and humidity readily cause root and stem rot. Growth is slow, and plants tolerate little disturbance to their deep roots. In cultivation it is grown in raised gravel beds, troughs, or alpine houses that keep the roots dry. It needs no fertilizer and only sparing water during its spring growth period. Wet winters are the main cause of loss outside its native range.Pruning
Pruning is not applicable to this slow-growing cactus. Damaged or rotted sections may be cut away with a clean blade to stop decay from spreading. No routine trimming is involved.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons