Michaelmas Daisy: How To Grow and Care For Aster Novi-belgi

Symphyotrichum novi-belgii (L.) G.L.Nesom [sim-fy-oh-TRY-kum, NO-vee BEL-jee-eye] is a flowering plant type species commonly known as Aster novi-belgi and Michaelmas daisy. 

The plant comes from the Aster family Asteraceae that includes:

Blooms of the Aster novi-belgi (Michaelmas Daisy)

S. novi-belgii is a native plant in North America, growing in eastern Canada (Quebec, New Brunswick, Newfoundland, etc.) and the northeastern United States, growing in abandoned fields and meadows. 

The scientific name is made up of the genus name Symphyotrichum and the species name novi-belgii, which means ‘from New York’. 

The reference comes from when the state was called Novum Belgium or New Belgium.

The common name New York Aster comes from the abovementioned reference. 

The other popular common name of the plant includes Michaelmas daisy. 

This name was given in the honor of St. Michael’s Day, which falls during the bloom time of this plant.

Michaelmas Daisy Plant Care               

Size & Growth     

New York asters are fast-growing plants. 

They are mound-forming, ranging in height from 12” inches to 6’ feet tall. 

Similar to flower color, the height and spread of the plant depends on the cultivar. 

Generally, plants growing in sandy soils are shorter and ones growing in rich loamy soils are taller.    

The plants are self-seeding, easy to grow, and known to flower profusely for several weeks.

Flowering and Fragrance

The plant puts on a great show from late summer to late fall. 

During this bloom time, eye-catching flowers are produced in multi-stem sprays.

These are a great source of nectar for pollinators.

The bloom color of the daisy-like double asters depends on the variety. 

Some produce pink flowers while others produce, white, and lavender-blue flowers.

Light & Temperature

The Michaelmas daisies are hardy to USDA Hardiness Zones 4 to 8. 

They grow best under the full sun but also tolerate partial shade. 

Place the plants under part shade or in a greenhouse when you are propagating new shoots.

Watering and Feeding

Asters love water but not overwatering. 

During warmer months, give enough water so the soil stays moist without excess water surrounding the roots for a long period. 

The plant is drought tolerant.

Use a light 2-2-2 natural fertilizer or good-quality organic compost in the fall.

Soil & Transplanting

The plants grow well in most light to medium soil types.

The mix you choose should have good soil moisture retention with good drainage. 

Also, avoid heavy clay soils and poor-drainage as it may cause wilt.

Also, provide good air circulation to prevent foliage diseases.

Transplanting isn’t necessary but is done in the fall when new shoots emerge. 

Be careful to choose an offset with sufficient underground stem. 

Bury them at the same height in individual pots until the plant develops strong roots. 

Plant them outside in the summer.

Grooming and Maintenance

New York asters are low-maintenance but some grooming is required. 

Pinch back the stems before mid-summer, promoting bushier growth and increased plant height. 

It will also help prevent flopping.

Cutting back growth and deadheading flowers before the flowering season ends helps curb self-seeding. 

On the other hand, cutting back may encourage extended flowering during bloom time.

How to Propagate Aster Novi-belgi Plant       

To propagate these asters from seed, surface sow in a cold frame. 

Pre-chill the seeds for about 2 weeks to improve germination. 

With proper watering and temperature approximately 68° degrees Fahrenheit (20° C), the seeds will germinate within 2 weeks. 

Once the seedlings are large enough, prick them out and plant in moist soil in individual pots in late summer.

Propagate by dividing the plants in spring or early fall. 

Plant large divisions directly in the locations you want them to grow in. 

Smaller clumps are be potted and put in a cold frame first.

The plant self-seeds pretty effectively, allowing you to harvest new shoots. 

Gently dig up new growth, taking shoots between 3.9” – 6” inches tall. 

Pot them in individual pots and keep in partial shade or a greenhouse until they establish roots.

Aster Novi-belgi Pest or Diseases

Michaelmas daisies are usually free of serious pest and disease issues and they are deer resistant. 

They are also unaffected by powdery mildew disease.

They may be susceptible to aster wilt, especially if the plants are not growing in the right USDA zone or poorly-drained clay soils.

Michaelmas Daisy Plant Uses

During the season of interest, these plants look incredible in fall gardens. 

Add them to rock gardens, cottage gardens, and as well as border fronts. 

The blue flowers of the New York Aster are known to attract pollinators such as butterflies, making them suitable for pollinator gardens.

These plants are also suitable for containers and often used for mass planting. 

Use cut flowers from the plants and add them to wildflower bouquets.