How to Water Klapper's hedgehog cactus?
Deep but infrequent watering, letting soil dry completely

Klapper's hedgehog cactus · Echinocereus klapperi
Grow under glass in a loam-based potting compost with added extra grit. Water moderately when in growth, not at all when dormant. Apply a balanced liquid fertiliser 2 or 3 times in the growing season see houseplant cacti and succulent cultivation
Deep but infrequent watering, letting soil dry completely