Echinocereus subinermis aka Hedgehog Cactus

Echinocereus subinermis is a small cactus from northern Mexico. Its range includes Sonora, Sinaloa, southwestern Chihuahua, and Durango. It belongs to the cactus family, Cactaceae. It grows in dry shrubland and desert regions. It also lives on rocky slopes and in woodland clearings. LLIFLE records it in oak forests that shed their leaves. Wild plants grow in sandy loam among volcanic rocks.

The plant starts with one stem and may slowly form clumps. Young stems are pale green, then turn blue-green. Older stems become dark green and may take on purple tones. Broad, rounded ribs run along each stem. Small, woolly areoles sit along these ribs. Young plants bear short spines; older plants may lose most. LLIFLE gives stem heights of 0.3–0.7 feet [0.1–0.2 metres]. The RHS describes stems reaching 0.8 feet [0.25 metres]. Its wider garden size range reaches 1.6 feet [0.5 metres], both tall and wide. Plants may take five to ten years to reach full size.

Large, funnel-shaped flowers open near the stem tips. Their petals range from cream to bright yellow. Some have reddish stripes down their centres. The flowers have green stigma lobes and a light, sweet scent. They span about 0.3 feet [0.1 metres], sometimes reaching 0.4 feet [0.12 metres]. The RHS places flowering in early summer. LLIFLE gives a broader spring-to-summer season. Each flower may last up to six days. Plants raised from seed may first bloom after four to five years. The grey-green fruit has spines and white flesh. It splits along its length.

Grow this cactus in full sun with shelter. The RHS recommends growing it under glass in Britain. Use peat-free, loam-based compost with extra grit for drainage. Water moderately during growth, then stop watering during dormancy. Feed with balanced liquid fertiliser two or three times during growth. Its RHS hardiness rating is H1C. This allows summer outdoor growing where temperatures remain above 41–50°F [5–10°C].

Its small size suits pots and sheltered patio displays. The large flowers give contrast against the ribbed stems. No pruning is needed, and seed offers a propagation route. Watch for mealybugs and scale insects. The RHS reports few disease problems. The supplied sources do not establish edibility or toxicity.