How to Grow and Care for New England Asters

New England asters

The Spruce / Letícia Almeida 

The New England aster (Symphyotrichum novae-angliae) is a standout fall flower. The plants feature erect stems that can grow several feet tall. The stems have fine “hairs,” or bristles, and sport many lance-shaped leaves extending from them. In the late summer to early fall, the profuse daisy-like blooms appear. The flowers are typically 1.5-inch in diameter, in a pinkish-purple color with yellow-orange centers. Pollinators love the blooms. In northern climates, you can plant New England asters from spring to early fall, and they should become established before winter. In southern climates, it’s best to plant them only in the spring and fall, as hot summer temperatures can be damaging to a plant that isn’t yet established. Asters are fast growers and will typically bloom in their first year. 

Common Name New England aster
Botanical Name Symphyotrichum novae-angliae
Family Asteraceae
Plant Type Herbaceous, perennial
Mature Size 3-6 ft. tall, 2-3 ft. wide
Sun Exposure Full
Soil Type Moist but well-draining
Soil pH Acidic
Bloom Time Fall
Flower Color Pink, purple, white
Hardiness Zones 4-8 (USDA)
Native Area North America
New England asters
The Spruce / Letícia Almeida  
New England aster bud
The Spruce / Letícia Almeida  
New England asters
The Spruce / Letícia Almeida 
field of New England asters
The Spruce / Letícia Almeida  
New England asters
The Spruce / Letícia Almeida  

New England Aster Care

New England asters grow naturally in a variety of sites, including prairies, marshes, and forest edges. Under ideal conditions, they will easily spread in a garden bed and make excellent mass plantings. If you select a growing site that gets lots of sun and has rich soil, the asters’ care needs will be minimal. Your main task might simply be watering when there isn't enough rainfall and the soil dries out.

Light

New England asters need a spot with full sun to grow and bloom their best. That means their growing site should get at least six hours of sunlight on most days.

Soil

These plants prefer rich soil with a slightly acidic soil pH and good drainage, but they can grow in other soil types as well. They’re even tolerant of clay soil.

Water

Like many other flowers, New England asters like moist soil. They can tolerate lower levels of soil moisture as long as it’s not completely dry to the touch. Water your plants well during stretches with no rainfall.

Temperature and Humidity

New England asters tend to grow vigorously throughout the climates of their USDA hardiness zones. Extremely hot weather can make the plants wilt, but they should come back fine once the temperature cools. Humidity generally isn’t an issue, though ensure that your asters will have good air circulation when planting them. Poor airflow plus high humidity can be a breeding ground for disease on plants.

Fertilizer

Plan to fertilize your asters in the spring when new growth appears. Use a water-soluble or granular fertilizer made for flowering plants. For the amount to use, follow the product label instructions. You also can enrich the soil with compost.

Types of New England Aster

There are many New England aster varieties, and most of them look the same but have different flower colors. Some of these include:

  • ‘Harrington’s Pink’: Rose-pink flowers
  • ‘Septemberrubin’: Purple-red flowers
  • ‘Alma Potschke’: Pink flowers
  • ‘Purple Dome’: Violet flowers
  • ‘Barr’s Blue’: Violet-blue flowers

Pruning

In the first part of the summer, pinching back stems every few weeks can promote a bushier and more compact growth habit. However, stop the pinching process by August, or you might accidentally take off some flower buds. If your asters become very tall and lanky, you might need to stake them to prevent the stems from flopping over. Then, cut the asters to the ground after they're done flowering and the foliage dies in the fall. This prepares your garden bed for new growth the following spring.

Propagating New England Aster

New England aster can be propagated easily by division, cuttings, or seeds. Many find that division is the safer route, as it's impossible to know for sure what the aster will look like when propagated from seed.

To propagate from division, wait until the aster plant is at least three years old. This ensures enough of a root system to easily divide without damaging the main plant.

  1. Use a shovel to cut into the clump, dividing it neatly into two parts.
  2. Replant the divisions immediately at the same depth they were growing previously.
  3. Feed them with bone meal or low-nitrogen fertilizer and water regularly until established.

Or, propagate New England aster by cuttings:

  1. Take a 5-inch section of stem from the healthy plant in early spring.
  2. Remove the lower leaves, keeping three or four of those at the top of the stem.
  3. Dip the stem in rooting hormone and place it in a pot filled with well-draining medium, like perlite or sand.
  4. Cover the cutting with a plastic bag to promote better humidity. Roots should develop within a matter of weeks.

How to Grow New England Aster From Seed

Though asters will readily self-seed in the garden, it's possible to collect the puffball-like seeds and germinate them indoors during the early winter. Sow seeds in well-draining potting soil and cover them with plastic for added humidity. They should germinate with a soil temperature of 65 to 75 degrees Fahrenheit.

Potting and Repotting New England Aster

When potting asters, choose a pot that is a little bigger than the aster plant. It should have excellent drainage. Plant the aster in well-blended compost, in a hole a little larger and deeper than the pot the aster was originally in. Cut back the plant after flowering and overwinter it in a cold frame or greenhouse. If the aster becomes root-bound, transfer it to a pot that is a few inches wider than the old one.

Overwintering

To help asters thrive, water the ground well before the first freeze hits. After the ground freezes, cut the asters back to the soil level and cover them with 2-3 inches of mulch.

Common Plant Diseases

Asters are generally hardy flowers, but they can be susceptible to powdery mildew. This is a fungal disease that leaves patches of white or gray powder on the leaves and stems of an infected plant. Check the undersides of leaves, as this is where it often first appears. In addition to the white or gray patches, the plant also might yellow, look withered, and lose leaves.

To treat powdery mildew, you can apply a fungicide labeled for the disease. It’s also recommended to prune off infected portions of the plant, especially if it’s only on a small area and hasn’t spread yet. Prevention is key, as well. To avoid powdery mildew problems with your asters, make sure there is good airflow among the plants. Thin your asters by dividing them every few years in the early spring or fall. Also, always water at their bases, not from overhead.

How to Get New England Aster to Bloom

If your New England aster isn't blooming, check the particular cultivar you have and make sure you are looking for blooms at the right time. If you are but there are still no signs of flowers, consider the age of the plant. Very young plants are still trying to establish a strong root system, and thus might not devote energy to flowers at all for the first season or two.

Finally, consider the fertilizer. Asters don't need much feeding, and they can easily have too much nitrogen from a typical fertilizer. That nitrogen can lead to lovely foliage but no blooms. Back off on the fertilizer and choose one with low nitrogen to see if that sparks a profusion of color.

Common Problems with New England Aster

A problem that is unique to aster plants is called "aster yellows." Despite the name, this can happen to other plants as well. It presents with stunted growth, the plant sending out secondary shoots, smaller and narrower leaves, and a "twisted" look to the leaves, as though they are drying up despite ample water. The colors of the plant will be off as well - the typical lovely colors will be severely muted, and the leaves will be a paler color than usual. Flowers might be very small or malformed. The aster won't produce any seed.

This problem is caused by the aster leafhopper, an insect that spreads a particular bacterium from one plant to another. The result is damage to the whole garden, but especially to the aster plants. Unfortunately, there is no treatment, and the best you can do is remove the affected plants immediately to prevent the bacterium from spreading further.

FAQ
  • How long can New England aster live?

    With proper care and attention to division every three or four years, an aster plant can live for at least a decade.

  • What are good companion plants for New England aster?

    Any aster plant looks lovely nestled among low-growing ferns. Brown-eyed Susans also make an impressive show alongside asters.

  • How many different varieties of asters are there?

    Currently, there are over 170 varieties of asters, and that's not including the wide array of hybrids.