In addition to the ones that I grow (see Asters, Part I) in my USDA zone 7 garden, there are many other aster species and cultivars that can provide color in your garden.
Actually, although I think of asters as end of the season plants, some, like Aster alpinus, flower earlier in the season.
Aster alpinus (Alpine Aster)
Flowering in late spring or early summer, this small -- six to twelve inch (15 - 30cm) tall native of the mountains of Europe, Asia and the western North America is a great plant for the front of the border or the rock garden. It is rated hardy from USDA zones 4 to 9, but does best where winters are cold. They prefer well-drained, alkaline soil and need sun.
Some of the species varieties are:
- dolomiticus, found on the Balkan Peninsula gets eight inches (20 cm)tall and has foliage with fine hairs held flatly against it;
- polycephalus, found in Switzerland has several flower heads on each stem with the terminal heads larger than the lateral ones;
- speciosus, found in Central Asia, gets up to twenty inches (50.8cm) tall and has larger flower heads than the species of a dark violet color;
- Wolfii, also native to Switzerland can get to one foot (30.4cm) or more in height and has blue flowers.
There are also several cultivars, some with semi-double flowers:
- 'Albus', of course, has white flowers;
- 'Coeruleus', which has blue flowers and gets ten inches (25cm) tall;
- 'Roseus' has pale rose flowers and is six inches (15cm)tall;
- 'Rubra' has rosy-purple flowers;
- 'Superbus' has larger and more showy heads of purple flowers;
- 'Dark Beauty' gets six to twelve inches (15 - 30.4cm) tall and has deep blue flowers;
- 'Goliath' gets fifteen inches tall and has soft blue flowers;
- Happy End' gets twelve inches tall and has semidouble lavender flowers.
Aster alpigenus
This is another alpine aster, native to the Cascade Mountains of Oregon and Washington. It gets seven inches (17.8cm) tall when in flower. Hortus III lists one variety, Hayenii, said to have more slender stems with leaves reaching four inches long and native to Eastern Oregon and north east Nevada to western Wyoming and Montana. I have not run across any cultivation information, but have to assume from the native locations and gravel soil in the photographs that this is a definite alpine and would require scree conditions and cold winters.
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