Asters are hardy perennials that are just getting started when other plants are wrapping up their bloom season. A favorite fall (autumn) flower, asters will bring much-needed color to the garden in late summer and will continue blooming until the first frost.
Use these tips to plant and grow asters so you can enjoy their colorful beauty for years to come.
Asters enjoy a sunny location but need a little shade from the afternoon sun in mid-summer. When selecting a planting location remember these plants won’t be in full bloom until tree leaves have already begun to drop and surrounding plants have ended their blooming season.
Asters are a little tricky to grow from seeds because you don’t know if the seeds have gone through the needed winter cold during their dormant stage. Without the cold dormant period, asters seed germination is unpredictable.
To get a higher rate of seed germination, place aster seeds in the refrigerator for 6 weeks before planting time to stimulate winter dormancy. Plant the seeds in the soil in late summer.
Potted plants purchased at your local nursery can be planted in-ground as soon as you bring them home.
How To Plant
Prepare soil by tilling to 12 inches (30 cm) deep. Add 2 inches (5 cm) of compost and lightly work that into the soil. Place seeds 1 inch (2.5 cm) deep and 1 foot (30 cm) apart. Place plants 1 foot (30 cm) apart also.
Water thoroughly at planting time.
Apply organic mulch around plants at planting time. When using seeds, apply mulch when plants are about 3 inches (7.5 cm) tall. Mulch will help keep the soil cool, help retain moisture, and prevent weed growth.
Asters can reach a mature height of anywhere between 8 inches and 8 feet, depending on the variety you plant. Taller plants will need to be staked to keep them upright.
Aster blooms are rich with pollen and attract pollinating bees and butterflies, making them an ideal flower to plant near a later season garden.
Keep the soil moist with regular watering. Fertilize once in the late spring.
Pinch top flowers off at least once to encourage lateral growth and more side blooms. Asters related to daisies and produce an open-faced multi-petaled bloom with large yellow center The most common bloom color is purple, but blooms can also be red, white, blue, pink, or yellow.
Cut plants back to the ground after the foliage has died in the winter.
Asters will re-seed themselves when blooms are not deadheaded, however, the resulting plant will not bloom true to the parent plant.