Tweedia Heavenly Blue - seeds

Tweedia 'Heavenly Blue' is an improvement of the botanical species also known as Oxypetalum coeruleum. It is distinguished by its longer flowering period and even bluer flowers. The flowers are small, but numerous and renewed for long months. The small star-shaped flowers are an exceptional sky blue, rare in the plant kingdom. This compact shrub, with a trailing habit and velvety green-grey foliage, thrives in full sun, in well-drained soil, even dry. It is not very hardy and should be grown in a pot anywhere other than south or west coastal areas.

The Blue Star, or Southern Star, in Latin Oxypetalum coeruleum is a member of the former Asclepiadaceae family (like the Stephanotis known to us as a houseplant), now integrated into the Apocynaceae family (which includes the Nerium, or Oleander, and Periwinkles). These are often toxic plants, but in Oxypetalum, only the sap can be irritating to the skin. This genus, which has only one species, is native to South America (Brazil and Uruguay).
In its native habitat, this herbaceous plant forms a small evergreen shrub with a creeping or semi-climbing habit, barely reaching a maximum height of 90 cm (35in), sometimes even only 30 cm (12in). Under our climates, the growth is a bit slow at first, but the plant eventually becomes more bushy during the season, you can pinch it occasionally to encourage branching. The velvety stems, which only turn woody at the base, remaining herbaceous in the upper part, are adorned with opposite leaves. They have an original shape, like a spearhead, and are very velvety like the stems, ranging in colour from grey-green to medium green. They measure from 3 to 6 cm (1 to 2in) long and 1 to 3 cm (0 to 1in) wide and are borne on short petioles measuring from 0.2 to 1.2 cm (0 to 1in).
The flowers can be solitary or grouped in umbels of 3 to 5, and measure from 2 to 2.5 cm (1in) in diameter. They are star-shaped and composed of five petals of an almost unreal sky blue, reputed to be even more intense in 'Heavenly Blue' than in the botanical species. This variety, introduced in 1986 by the Sahin company, has established itself in the ornamental market because of the duration of its flowering, which extends from July (sometimes even June) until October, or even until the first frost.
If the plant is grown in a pot and overwintered indoors, the foliage will persist on the plant, outdoors, it will dry up when the temperature drops a few degrees below zero, and the crown will be destroyed at around -8 or -10°C (17.6 or 14°F).

Tweedia 'Heavenly Blue' will fit well in sunny rock gardens, in well-drained soil, and even dry. You can combine it with other ornamental plants with similar needs, such as Euphorbia myrsinites, or Myrtle Spurge, with its sculptural bluish foliage, enhanced by a spring flowering that creates a harmony of chartreuse green and golden hues. Those who like strong contrasts can add a few clumps of Armeria maritima Düsseldorfer Stolz, a Sea Thrift with low, dense tufts covered in small, vibrant pink flowers during the same period as the Oxypetalum. And to play with foliage, Berberis thunbergii Lutin Rouge will be ideal with its miniature size, only 60 cm (24in) in all directions, and its red to purple foliage, which is adorned with delicate yellow flowers in May and June.