Origin and appearance
The genus of star umbels (Astrantia) is a very small group – it comprises only 10 different deciduous species, of which there are numerous varieties. The perennials of the umbellifer family (Apiaceae) are native to alpine meadows and forests in Europe and Asia. Among the smallest species is the small star umbel (Astrantia minor) with a growth height of between 15 and 40 centimetres, while the giant star umbel (Astrantia maxima) can reach a height of up to 90 centimetres.
From a horticultural point of view, however, only half of the species are interesting. These include especially the higher species such as the Bavarian star umbel (Astrantia bavarica), the Carniolan star umbel (Astrantia carniolica), the great star umbel (Astrantia major, large photo above) and the giant star umbel. These four species differ mainly in their flower size. While the Bavarian and the Carniolan star umbels bear small umbel flowers that are only up to 2.5 centimetres in diameter, the flowers of the giant star umbels can reach up to 4 centimetres. The most striking flowers, however, are those of the giant star umbel, which can be up to 9 centimetres in diameter, depending on the variety. Because of its magnificent flowers, a particularly large number of varieties of this species have been bred in the past. The colour spectrum ranges from white to delicate pink tones and deep red. In recent years, numerous dark red flowering varieties in particular have been bred and introduced to the market. The flowers themselves consist of a simple, dense umbel surrounded by a wreath of bracts. Depending on the species and variety, they open between June and September and then decorate the plant for several weeks. In recent years, star-shaped umbels have become popular cut flowers, as they give every bouquet a natural charm. The leaves are lobed and there are always several coming from a common centre.
Star umbels feel most comfortable in a sunny or semi-shady place in the garden, which is also humid. They love nutritious soil that is always well supplied with water.
Because of their wild perennial character, star umbels are particularly suitable for natural planting in light semi-shade. With their elegant, sometimes filigree umbels, they lend lightness to any planting here. As they thrive well in partial shade, the species and varieties can be used very well for underplanting deciduous shrubs. For example, tone-in-tone plantings with the dark red flowering varieties of the large star umbels, such as ‘Claret’ or ‘Haspen Blood’, combined with other red-flowering or red-leaved perennials, such as purple bell (Heuchera) or angelica (Angelica), are particularly attractive. But also with grasses such as the sneezels (Deschampsia) there are beautiful combinations with natural charm.
Star umbels thrive best in a soil rich in humus and nutrients. If the soil at your desired planting location is too meagre, you should enrich it with some compost before planting.
To prevent self-sownowning, the withered inflorescences of the large star umbels should be cut off directly. This is because this species tends to spread unhindered in an optimal location.
In particular, the varieties of star umbels should be propagated by division rather than by seed in order to maintain the characteristics of the variety. This is best done in spring or after flowering in late summer to autumn.
Further care tips
Star umbels prefer always a slightly moist soil. If the perennial is planted in a sunny location, it should, therefore, be watered regularly.
In autumn you can sow the fresh seeds of the star umbels. However, they will not germinate until the following spring, as they need a cold stimulus before that. The perennials can also be divided.
Diseases and pests
Star umbels are not very susceptible to plant diseases and pests, but are occasionally attacked by leaf miner moths or get leaf spots from fungal attack. Snails are usually not a problem.