Echinocereus rigidissimus var. rubrispinus is commonly called the rainbow hedgehog cactus and best known for its beautiful pink coloration. This petite plant typically grows to reach 30 cm tall by 11 cm wide. Aptly named, it bears new spines that are magenta colored and fade to yellow or light pink with maturity. Echinocereus rigidissimus grows as a stocky, solitary stem, rarely producing offsets. Endemic to parts of northwest Mexico and southwest United States, it can be found growing on rocky slopes at high elevation.
Echinocereus rigidissimus are desert cacti that require full sun. Eight hours of direct sunlight a day is ideal but at a minimum these plants should be provided with at least five hours. The more sun this cactus receives, the more brilliant the spine coloration will become. Echinocereus rigidissimus plants are extremely drought tolerant. Water them thoroughly, fully saturating the soil. Always allow the soil to dry out completely in between waterings. If you are unsure whether or not the soil is dry, wait a few days before watering. Always check your local weather before watering indoor arid plants in winter. It is best to water if there is a stretch of sunshine in the forecast.
Echinocereus rigidissimus var. rubrispinus flower in the spring, from late April to early June. Flowers buds are borne in clusters from the top of the cacti. Blossoms are bright pink in color. Rainbow hedgehog cacti do not require fertilization, however a boost of nutrients during the growing season will help them thrive. Use a fertilizer formulated specifically for cacti and succulents, once a month, during the spring and summer only.