Southern Star, Star of the Argentine

Southern star, also dubbed star of the Argentine, is worth looking at closely -- its buds are pink, opening to a silvery blue star that fades to purple and then to lilac as it ages. The shape of the flower is an exquisite 5-pointed star. A shrubby perennial plant from Argentina, it's used here as an annual except in nearly frost-free parts of Hardiness Zones 9 and 10 where it will winter over in permanent plantings. It's a member of the milkweed family.

Description of southern star: Used as an annual, it has a somewhat different character than its sub-shrub form in permanent plantings. Young plants have somewhat twining stems topped by clusters of flowers 1 inch in diameter. It can grow to 3 feet in nature, but rarely tops 18 inches in the garden.


Growing southern star: Southern stars do best in rich, well-drained loam in full sun. Space plants 6 to 8 inches apart. Pinch the plants once or twice to induce bushiness. In midsummer, they can be cut back about halfway to force new growth and extra bloom. Just before frost, plants from the garden can be dug, cut back, repotted, and grown for winter color on sunny windowsills.

Propagating southern star: By seed or cuttings. Plants will bloom about 8 weeks after germination. For early bloom, sow indoors 6 to 8 weeks prior to planting in the garden after all danger of frost has passed. Seeds will germinate in 10 to 15 days at 70 degrees Fahrenheit. Seeds may also be sown directly in the ground outdoors, although this will delay bloom until late summer, except in milder areas.

Uses for southern star: Plant them beside pathways and sidewalks or at eye level on banks or above walls for close-up viewing. Use them in containers. Because their growth is upright and somewhat spreading, trailing plants make an attractive addition to containers. Southern stars may also be brought indoors for winter bloom.

Scientific name of southern star: Oxypetalum caeruleum

Want more information? Try these links:

  • Annual Flowers. Discover your favorite annual flowers. We've organized them by color, sunlight, soil type, and height to make it easy to plan your garden.
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  • Perennial Flowers. Complement your annuals with these delightful perennial flowers. They are also organized by height, soil type, sunlight, and color.