Asters

Asters grow and flower best in full sun. Some varieties will tolerate part shade but will have fewer flowers. Soil should be moist but well-drained, and loamy. Wet clay soil will lead to root rot and dry sandy soil will lead to plant wilt. Mix 2 to 3 inches of compost into the soil prior to planting. 

When to Plant Asters

• Asters are most often bought as a potted plant. The best time to plant young asters is in mid- to late spring. Look for asters in the perennial sections of your garden center for the best selection.
• Full grown and blooming asters also can be found in garden centers in late summer for fall decoration. Plant them in pots or in the ground as soon as possible after purchase so they can get established.
• Asters can be grown from seed, but germination can be uneven. If desired, plant seeds outside in the fall, or start them indoors in winter in flats and refrigerate them for 4 to 6 weeks to simulate winter dormancy. Seven to 8 weeks before planting, place the pots/flats in a sunny spot with a temperature of 60º to 62ºF. Transplant seedlings outside in mid- to late spring after the danger of frost has passed. (See local frost dates.)

How to Plant Asters

• When planting young aster plants, space them 1 to 3 feet apart, depending on the type and how large it’s expected to get.
• Fully grown asters, such as those available in late summer or early fall, should be planted about 3 feet apart.
• Asters prefer areas with cool, moist summers, as well as cool nights, in sites with full to partial sun.
• In warmer climates, they do not like the hot midday sun.
• Give plants plenty of water at the time of planting.
• Add mulch after planting to keep soil cool and prevent weeds.