Say it: ek-ih-NOP-sis ox-ih-GOH-nuh / sub-den-yoo-DAY-tuh. Common names: Easter lily cactus, domino cactus, sea urchin cactus.
Where it grows
Echinopsis oxygona comes from southern Brazil, Uruguay and northern Argentina; E. subdenudata from Bolivia and Paraguay; and Helianthocereus grandiflorus (now usually Echinopsis huascha or Trichocereus grandiflorus) from the mountains of northwestern Argentina.
Size and growth
Oxygona is a ribbed green globe to 10 inches that clusters freely. Subdenudata is a neat, nearly spineless dark globe with tufts of white wool at each areole, like dominoes — usually under 4 inches. Grandiflorus forms clumps of short columns a foot or two tall. All grow at a moderate pace and flower young.
Flowers
Spectacular. Oxygona throws out long-tubed pink flowers 6 inches across, scented, open overnight into the next morning. Subdenudata's are pure white and fragrant at night. Grandiflorus blooms by day in fiery red, orange or yellow, 3 inches wide, in repeated flushes through summer. Flowers in 2–3 years from seed for the globular species.
Care
- Light: bright light to full sun; some shade in desert heat.
- Water: regular in summer, dry in winter.
- Soil: gritty with some organic matter.
- Cold: around 20°F if dry. A cool, dry winter is what triggers the big spring flush.
From seed
Easy. Germination in 7–14 days, and seedlings grow fast. Variegated oxygona seed gives a share of variegated seedlings.
E. oxygona seeds · E. oxygona variegata seeds · Domino cactus seeds · Helianthocereus grandiflorus seeds