Growing Aster Flowers: How To Care For Blooming Aster Plants

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Asters (ASS-ter) are late-blooming herbaceous perennial members of the Asteraceae (ass-ter-AY-see-ee) plants native to Europe, Asia, and North America.

The plants’ name originates from ancient Greek. It means “star” for the star-shaped blooms of this pretty, versatile garden favorite.


Depending upon the cultivar in question, you may also hear this plant called Frost Flower, New England Aster, New York Aster, or Alpine Aster.

The plant’s botanical name is Symphyotrichum spp.

Size And Growth

Asters are generally easy-going and fast-growing. Their ultimate size depends very much upon the type of plant.

Alpine Asters tend to be low growing with a mounding growth habit. Other varieties range in height and spread from 3′ feet to 5′ feet.

Flowering And Fragrance

The star-shaped blooms come in many variations in red, blue, purple, pink, and white. Some have sparse, spiky petals; others have fluffy double and triple petal formations.

Most Asters bloom late in the summertime and into the autumn months. Alpine Asters bloom in the springtime.

Light And Temperature

Generally speaking, Asters do well in part-to-full sun locations. They are winter hardy in USDA hardiness zones 3-8.

Asters do best in climates that provide:

  • moderate summertime temperatures with cool nights
  • regular rainfall
  • some shelter from harsh sunlight in hotter climates

Watering And Feeding

Provide a thorough watering when you plant your Asters. Keep the soil moist until the plants are established with a recommended 1″ inch of water.

Avoid overhead watering or vigorous watering that allows water to splash up from the soil onto the plants. Slow watering with a soaker hose is best.

Be careful not to overwater as this can cause leaf drops and reduced blooming.

Apply a balanced plant food formula once or twice monthly throughout the spring and early-to-midsummer. Suspend fertilizing in August because the use of fertilizer may shorten bloom time.

Soil And Transplanting

Asters like well-draining, loamy soil mixed with good organic compost. It’s best to mix amendments into the ground before planting.

Plant new Asters in the springtime after all danger of frost has passed. Give them plenty of room for air circulation and growth. A distance of 1′ – 3′ feet between plants is best.

After planting, surround your new plants with a 2″ inch layer of organic mulch. Take care not to allow the mulch to touch the plants’ stems.

Mulch holds moisture in the soil and breaks down gradually to help supply the plants with valuable nutrients.

Early springtime, refresh the soil surrounding established plants with a thin layer of organic compost. Follow up with another mulch application.

Grooming And Maintenance

Asters are very easy-care plants. Depending upon the variety you choose, you may need to prune or stake them to prevent toppling and promote bushy growth.

Regular deadheading promotes better blooms in all varieties.

Pinching back branch tips promotes thick, full foliage.

After blooming is complete and foliage has died, you may wish to cut your Asters back to the ground for winter. Alternately, you can leave them in place for winter interest.

How To Propagate Asters?

It is possible to grow Asters from seed, but germination is unreliable. For this reason, most people buy young plants early in the springtime.

Mature plants allowed to go to seed may self propagate, but the blooms of the offspring may not resemble those of the parent plants.

Asters can also be grown from stem cuttings or through root division. It’s a good idea to divide mature plants every couple of years to prevent overcrowding.

Asters Pest Or Disease Problems

Aster Yellows is a viral infection spread by pests, such as leafhoppers. It causes erratic growth, along with deformed blooms with green petals.

To prevent it, be sure to control weed growth around your Asters, and take steps to control pests.

Asters planted in less than ideal settings, overwatered, or overcrowded, may be more vulnerable to pests such as:

  • Cabbage Loopers
  • Leafhoppers
  • Spider Mites
  • Leaf Miners
  • Aphids

To prevent and control infestation, take steps to encourage natural predators, such as ladybugs and beneficial wasps. Keep plant debris and weeds under control, and apply insecticidal soaps as needed.

Overcrowded, overwatered plants are also subject to several fungal infections, including:

  • Powdery Mildew
  • Fusarium Wilt
  • Botrytis
  • Rust

To prevent fungal infection, provide ample spacing between plants, avoid overwatering, and don’t overhead water. Prune away dead and damaged leaves and branches. Remove and destroy plants affected by pernicious soil-borne fungal infections (i.e., Fusarium Wilt.)

Is The Plant Considered Toxic Or Poisonous To People Or Pets?

Asters are not only non-toxic; they are edible. You can include the blooms in salads and the leaves in herbal teas.

Is the Plant Considered Invasive?

Plants in the Asteraceae family of plants are generally enthusiastic growers and spreaders. They are spread by seed, stem rooting, and root spread.

Although Asters are not termed invasive, they are aggressive and can make themselves unwelcome if not kept under control.

For this reason, it’s a good idea to keep a close eye on them. Mow or pull up wanderers to prevent them from invading your neighbors’ yards.

Suggested Asters Uses

Depending upon the type of Asters you choose, you can count on these pretty plants to add lots of late-season color to your landscape. They do well in:

  • Butterfly and Pollinator Gardens
  • Containers and Planters
  • Naturalized Settings
  • Border Plantings
  • Cutting Gardens
  • Herb Gardens

Your use of Asters is only limited by your creativity.

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