Mammillaria microhelia is a species of plant in the family Cactaceae. It is endemic to Mexico and grows at elevations of 2,000 to 2,600 metres above sea level. Mammillaria microhelia is considered to be Endangered due to its limited range.
Mammillaria microhelia is a particularly attractive small columnar, perennial cactus both solitary or forming clumps and bearing cream or brown spines, discolouring with age. Has creamy-white to purplish flowers in spring. Spines are arranged like the rays of the sun. These stems are cylindrical, medium green, to 15(-25) cm or more high, 3-5(-6) cm in diameter. In good conditions with careful application of water and excellent ventilation Mammillaria microhelia grows without difficulty. It is a slow growing species that rewards the patient grower with a beautiful displays of flowers since from an early age.
Water should be carefully applied and only when the soil is dry to the touch, as this cliff-dwelling species is very prone to root rot. Allow soil to drain thoroughly before watering again. Do not water in the winter.
Outside full sun or afternoon shade, inside it needs bright light, and some direct sun. Direct sun encourages flowering and heavy spine production.
The plant requires good drainage provided by a very permeable open cactus soil (with not less than 50% grit content). Reduce the use of peat or other humus sources in the potting mixture.
During the blooming season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.
Protect from frost. But it's hardy to -5°C if kept dry. A winter rest that allows the plant to shrivel (perhaps losing up to 25% of its summer height) will encourage flowering and long time survival. Inside, average room temperatures of 20 to 22°C (68 to 72°F) will suffice.
