Growing New York Asters: How to Care for Michaelmas Daisies

Symphyotrichum novi-belgii

The New York aster, Symphyotrichum novi-belgii, is a showstopper in the late season garden, taking center stage as summer flowers fade to memories.

We link to vendors to help you find relevant products. If you buy from one of our links, we may earn a commission.

Native to the eastern United States and Canada, with blooms that are lavender in the wild, it is one of the most extensively cultivated asters and varieties are available in a palette of vivid pinks, purples, and crisp whites that light up the landscape.

Our guide to growing asters provides an overview of species and cultivation.

The focus of this piece is on how to grow and care for New York asters specifically.

Ready to dive in? Here’s what we’ll cover:

Let’s begin with an overview of the species.

What Are New York asters?

The New York aster was formerly classified in the Aster genus. And while you’ll still come across it categorized in this way, it was officially reassigned to the Symphyotrichum genus in the 1990s, where it remains.

And while we still call our native species asters, the New York variety also has a nickname, the Michaelmas daisy, because it blooms near the Christian feast day of Saint Michael on September 29.

There are three varieties of the New York species found in the wild, S. novi-belgii var. novi-belgii, S. novi-belgii var. elodes, and S. novi-belgii var. villicaule.

These plants have a clumping growth habit, and alternating lance-shaped leaves line branching stalks. The stems and leaves are generally green to grayish-green but may have a burgundy tint. As they age, the lower leaves often turn yellow.

The stalks have lateral branches. Each stalk develops one composite flower at its terminal end consisting of a yellow disk of florets surrounded by colored petal-like rays. Like many wild asters, the flowers measure about an inch in diameter.

The species name, novi-belgii, means New Belgium, aka New Netherland, the name of present-day New York when it was a Dutch colony in the 1600s.

Planting

Starting with a nursery plant is an excellent way to ensure that you are getting the variety you want, especially if you purchase it in late summer when it’s in bloom.

Transplant a seedling, stem cutting, or nursery plant in late spring or early fall to avoid damaging frost and peak summer heat.

Place plants in the ground at the same depth they were in their original containers to minimize transplant shock.

How to Grow

Plants are suited to garden and container cultivation because the height variations achieved through hybridization make it easy to select certain sizes to suit your gardening needs.

Let’s look at the ideal growing conditions to help your asters thrive:

Light

To ensure the best flowering, plant New York asters in full sun. They need at least six hours of direct light daily.

While they can tolerate some light shade, too much shade will reduce bloom production and can make the plants leggy.

In regions with hot summers, a touch of afternoon shade won’t hurt.

Soil

The soil should be organically-rich loam that is both moisture retentive and well-draining, with a pH of 5.1 to 6.8.

These plants can adapt to clay and sandy soils, and occasional oversaturation and drought.

Temperature and Humidity

Provide good spacing to promote air circulation and reduce the risk of disease.

Water

Keep the soil consistently moist, especially during dry spells in the growing season.

Once established, they’re moderately drought tolerant, but regular watering will result in more vigorous growth and better blooms.

Avoid overhead watering to help prevent foliar diseases—soaker hoses or drip irrigation work well here.

Fertilizer

Start with compost-enriched soil and, if needed, apply a balanced, slow-release fertilizer in early spring as new growth emerges.

Avoid over-fertilizing—especially with high-nitrogen formulas—as this can result in excessive leafy growth at the expense of flowers

Take care to avoid allowing the granules to touch plant tissue, and be sure to water over the fertilizer per package instructions.

Container Growing

New York asters can be grown in containers, though they may need a bit more attention. Choose a pot that’s at least 12 inches deep and wide, with good drainage.

Cultivars to Select

There are many brightly-colored New York cultivars from which to choose. Each is identified by a botanical name, such as A. novi-belgii or S. novi-belgii, followed by a cultivar name.

Disease-resistant hybrids offer the best chance for success, as this smooth-leaf species and its cultivars are more prone to fungal conditions, like powdery mildew, than their hairy counterparts.

Here are three vibrant choices to consider:

Alert

Suited to Zones 4 to 9, S. novi-belgii ‘Alert’ is a dwarf variety with bright pink flowers often described as red.

Each has a double row of luscious rays surrounding a rich golden disk. Plants have a moderate rate of growth.

‘Alert’

Mature heights are a petite 12 to 15 inches with a modest spread of 15 to 18 inches, making this the perfect plant for containers or tidy beds. Leggy stems won’t be a problem with this type.

‘Alert’ plants are available from Nature Hills Nursery.

Professor Kippenburg

S. novi-belgii ‘Professor Kippenburg’ is suited to Zones 3 to 8. It boasts purple flower heads. And unlike the one-inch diameter of many asters, the Professor measures a generous one to two inches across, with double rays and a sunny center.

‘Professor Kippenburg’

Fast-growing plants achieve a height of 18 to 20 inches and a spread of 12 to 18 inches, making them well-suited to mid-story landscape placements.

‘Professor Kippenburg’ plants are available from Nature Hills Nursery.

Woods Pink

Fast-growing Aster x dumosus ‘Woods Pink’ is a hybrid that grows in Zones 4 to 8 and displays semi-double pink blossoms with classic yellow centers.

‘Woods Pink’

Plants have a height and width of 12 to 24 inches for a substantial swath of vivid low-profile color.

‘Woods Pink’ plants are available from Nature Hills Nursery.

Woods Purple

Aster x dumosus ‘Woods Purple’ is also well-suited to Zones 4 to 8, where its purple blossoms enrich the transitional landscape with much-needed color.

‘Woods Purple’ 

Like ‘Woods Pink,’ this variety grows fast and has mature dimensions of 12 to 24 inches tall and wide, making it an excellent choice for bedding.

‘Woods Purple’ plants are available from Nature Hills Nursery.

Maintenance

Cultivars vary in height but are generally shorter than the six feet a native species can achieve.

For those that top out at two feet or more, prune in early summer for a bushier, less leggy appearance. In early summer, use clean pruners to remove one-third of the total height.

Instead of pruning, you can use twine and bamboo or metal garden stakes to support lanky stems.

Healthy plants spread via thick roots called rhizomes as well as seeds. It is easy for them to become overcrowded.

To maintain adequate air circulation and avoid fungal diseases, divide asters every three years.

Divisions make great gifts to fellow gardeners.

Overwintering

After the first hard frost, cut all stalks down to a height of about two inches. Use clean, sharp shears to make smooth cuts.

While it’s nice to have winter interest in the form of picturesque bare stalks and seed heads, a plant so prone to powdery mildew as this one should be completely cleared away and discarded to limit overwintering mold spores.

Propagation

It’s easy to start with seeds or stem cuttings. Here’s a quick overview of each of the methods.

From Seed

You can grow true species plants from collected seed, but seeds from hybrids produce variable results that may not resemble the parent plant. Sometimes cross-bred flora produces seeds that are not viable, or no seeds at all.

To grow true species from seeds:

1. Start seeds indoors in late winter, or direct sow after the last average frost date.
2. Fill a seed starter tray with potting soil.
3. Place two seeds in each cell.
4. Barely cover the seeds with one-eighth of an inch of potting soil.
5. Place the tray in a sunny window.
6. Keep the soil evenly moist.
7. When the seedlings have two sets of true leaves, thin them to one per cell.

From Cuttings

A stem cutting replicates the characteristics of the parent.

Here’s how to propagate from cuttings:

1. In late spring or early summer, make a clean cut across a stem about six inches from the tip. A clean cut is less likely to invite pests and disease than a ragged one.
2. Snip the leaves off the bottom four inches of the stem.
3. Place the bare stem in four inches of water.
4. Change the water daily and keep all foliage above the water surface to avoid fouling it.

Alternatively, dip the bare stem in rooting hormone and bury it four inches deep in a container of potting soil with a depth of at least six inches.

For more detailed propagation instructions here.

Pests and Disease

Unfortunately, S. novi-belgii is prone to a host of pests and diseases.

Some common pests to be familiar with include:

• Aphids
• Chrysanthemum Lace Bugs
• Cucumber Beetles
• Leaf Miners
• Nematodes
• Slugs and Snails
• Tarsenoid Mites

Plant pollen-rich plants to attract beneficial insects that feed upon pests. You can use neem oil, an organic horticultural insecticide, to address most infestation issues.

Diseases common to S. novi-belgii are:

• Aster Yellows
• Leaf Spot
• Powdery Mildew
• Rust
• Stem Canker
• White Smut

A sharp spray of the hose may dislodge pests. An application of organic insecticidal neem oil may also be effective.

And as mentioned, powdery mildew is especially common. However, it generally affects the foliage and doesn’t disrupt blooming.

If you have trouble getting your plants to bloom, check out our aster troubleshooting guide.

Best Uses

Today’s cultivars tame a tall wild aster for garden use. Dwarf varieties make a compact addition to beds and containers, whereas more statuesque versions provide an arresting sight when massed in a monochromatic drift or mixed wildflower meadow.

Fellow late-season bloomers – black-eyed Susans, coneflowers, goldenrod, joe-pye weed, ornamental grasses, and other asters – look beautiful with S. novi-beglii.

Mix them attractively in butterfly, cottage, and cutting gardens, where they feed local bees, butterflies, and songbirds.

I Love New York

Like the lights of the Great White Way, the bold, saturated colors of the New York aster shine in the late summer to autumn landscape, filling the interlude with masses of delightfully dazzling pinks, purples, and whites.

After waiting patiently in the wings all summer long, the landscape becomes their stage, providing a foliar backdrop to earlier bloomers.

Add the New York variety to your garden planner. And as the curtain draws to a close for the season, rest assured they’ll return for an encore performance each year for many to come.

Do you grow this flower at your house? Tell us about it in the comments section below.

And for more information about growing asters in your garden, add these articles to your reading list next:

• 13 of the Best Companion Plants for Tall Late Season Asters
• 11 Perennial Aster Species for Summer’s Last Hurrah
• How to Grow and Care for Calico Aster in the Late Summer to Fall Garden