Echinocactus grusonii
Light: Full sun to light shade; afternoon shade helps prevent scorching in Phoenix, especially for young or newly planted specimens. Acclimate gradually to direct sun.
Water: Low water; let soil dry completely between deep waterings. Established plants benefit from occasional summer irrigation during prolonged dry heat. Keep nearly dry in winter.
Soil: Very well-drained, gritty or gravelly soil. Use cactus mix with added mineral grit in containers; avoid water-retentive soils and low spots.
Mature size: Typically 2–3 feet tall and 2–3 feet wide; very old specimens may grow taller.
Bloom: Flowers in late spring through summer on mature plants, often after 15–20 years or longer.
Evergreen / deciduous: Evergreen succulent cactus.
Growth rate: Slow.