How to Water Pterocactus tuberosus?
Moderate regular watering, allowing brief slight drying between soakings

Pterocactus tuberosus · Pterocactus tuberosus
Under glass, grow in standard cactus compost with full light. From spring to late summer, water moderately and apply a low-nitrogen fertiliser every 4 or 5 weeks; keep almost dry at all other times. See houseplant cacti and succulent cultivation
Moderate regular watering, allowing brief slight drying between soakings