Aster Plant Facts

Types

• All asters were classified as one genera until scientific authorities broke them into two separate taxa: symphyotrichum and aster. Species in the genus aster only grow in parts of Europe and Asia, with one exception. The alpine aster (Aster alpinus), the only member of the aster genus that is native to North America, is found in northwestern Canada and the Alaska. The majority of asters in Symphyotrichum are native to the United States and Canada. According to a publication through North Carolina State University, most asters cultivated for use in gardens in the United States are bred from the New York aster.

Characteristics

• Aster plants often grow to several feet in height, some larger species may reach 4 to 5 feet high while smaller species are 1 to 2 feet. Many asters have a larger lateral spread than vertical height, often extending 3 to 6 feet in each direction. Asters are known for their showy flowers that can bloom in a variety of colors, including white, purple and several shades of red. Their foliage emerges as blades that grow around 3 to 4 inches long.

Environment and Hardiness

• Depending on the exact species, an aster can be grown in climates throughout the United States. Many species are hardy in zones 5 through 9, and some can survive in even warmer or colder climates. Both the white panicle aster (S. lanceolatum) and smooth blue aster (S. lavae) are hardy in practically every U.S. state. According to a publication by the University of Florida, asters require moist and well-drained soil to produce vibrant blooms, but they can survive in areas with relatively dry soil.

Pests and Diseases

• Asters are vulnerable to harmful insect pests, fungal agents and bacterial illnesses. They can be attacked by common pests such as aphids, leafminers and scales. Several serious pests, including the corn earworm and whiteflies, can also affect asters although they are not the preferred host of those species. Aster yellows is a serious illness of asters and several other groups of flowering plants, including some daisies. According to a webpage on the University of California website, asters can also become infected with the tomato spotted wilt virus and Fusarium wilt, which is caused by the Fusarium oxysporum fungus. Both of these diseases are contagious and are capable of killing their host.