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Growing and Caring for Aster Flowers


Purple aster flowersPurple aster flowers

Like many plant lovers, I cannot get enough of the aster flower.

Its vibrant purple, white, or blue daisy-like flowers surrounding a bright yellow center make it a popular choice for avid gardeners.

Various gardeners, including myself, take proper care of this resilient flower and enjoy its full bloom. But you may wonder, what is the right way to plant asters?

Through this comprehensive guide, I will help you discover ways to ensure your asters bloom during their growing season. I will also provide important tips and rules for growing your aster flowers properly wherever you are.

What Is an Aster Flower?

  • Other Common Names – Asters, New England asters, New York asters, frost flowers, Michaelmas daisies
  • Natively Found In – Eurasia
  • Mature Height – 1-6 feet tall, 1-4 feet wide
  • Hardiness Zones – Zones 3 – 8

Purple aster flowers in the gardenPurple aster flowers in the garden

Aster flowers are part of the Asteraceae family. They are known for being frost-hardy perennials with daisy-like flowers surrounding a yellow center.

The name aster comes from an ancient Greek word meaning “star.” I love this plant’s vibrant colors, which range from deep purple to white and blue, depending on its variety.

This flower grows around late summer to early fall, making it a perfect addition to any fall garden! Depending on the region, some variations may bloom by early summer. Asters grow best under the full sun, while other varieties prefer partial sun.

The aster flower symbolizes love and patience. Asters are perennials, so they last longer than other plants.

It’s also called a Michaelmas daisy as it often blooms around September 29, the feast day of St. Michael.

Different Aster Types

While some believe most asters are only deep purple and yellow, the colors of asters will vary depending on the variety.

Though there are over 600 aster varieties, there are two common types.

The first is the New England aster (Symphyotrichum spp.) The New England aster was also formerly known as aster novae angliae. This is a native species in North America and can grow up to 5 feet in height.

Selective focus of purple New England aster flowersSelective focus of purple New England aster flowers

They bloom during fall, and these tall asters have colors ranging from soft pink to the popular purple.

The other most common type is the New York aster plant (S. novi-belgii). These plants are somewhat shorter than other tall varieties of aster, averaging around two feet tall. They bloom during late summer and early fall.

Selective focus on the purple flowers of New York Aster plantSelective focus on the purple flowers of New York Aster plant

Regardless of the variant you have, asters are versatile. They may grow in rock gardens, borders, or wildflower gardens. They prefer loamy soil and quickly attract late-season pollinators like butterflies and bees.

If you want to see more variations of asters, check your local garden center.

Plant Care Tips

While the aster plant is always a worthy addition to your garden, you may need to know its specific needs.

Like all flowering plants, asters require care, maintenance, water, and sunlight. But how much do they need, and what should you avoid?

I’ll give you essential care tips to help you plant and care for asters correctly.

Watering Schedule

Regular watering is necessary when caring for young plants, and asters are no exception.

To help these flowers bloom continuously, water them at least once a week in the morning and place them in well-draining soil.

Ensure you allow the flowers to breathe between watering sessions to avoid overwatering.

Water only at the base of the plant. Asters want their foliage or leaves to remain dry, and watering directly from above the plant causes moisture to stay on its petals. When this happens, fungi and moisture may affect your asters.

Even when it starts to get warm from the early spring to the summer season, avoid overwatering the plant. Always check the soil before watering.

Watering aster flowers with a green watering canWatering aster flowers with a green watering can

Asters are sensitive to too much or too little moisture, especially certain hybrids.

If the plants lose flowers after watering or have fewer flowers than before, try a different watering method and ensure they aren’t exposed to direct sunlight.

Preferred Soil Types

I’ve found Asters love loamy soil, as this soil type allows enough water, air, and nutrients to flow through the flower. Placing them in a potting soil mixed with peat is recommended, which increases the air and water flow within the pot or earth.

Placing the asters in the correct soil type is incredibly important, as your potting soil could dictate whether the plant will bloom.

Remember to avoid dry sandy soil and wet clay soil, as these types significantly affect the asters’ growth. Using these soils may lead to root rot and plant wilt.

When planting asters in fall gardens, ensure they’re spaced 1 to 4 feet apart.

This spacing gives enough area for the flowers’ roots to grow properly. Since the roots are tough, use a sharp spade to ease the process.

I recommend adding mulch onto the soil of new plants to help prevent weeds.

Fertilizing Schedule

Young aster seedlings on a tray pot with fertilizerYoung aster seedlings on a tray pot with fertilizer

Like many plants, asters need fertilizer to boost their growth. They’re moderate feeders during their summer to fall growth season, so it’s best to fertilize them more during these times.

Organic fertilizers, like compost or well-rotted manure, will help these flowers grow to their full potential.

Slow-release fertilizers are also beneficial, as they can remove the need to fertilize your asters constantly. Slow-release fertilizers will help the soil maintain the fertilizer longer without harming the flowers.

Though asters require fertilizing for better growth, remember to avoid over-fertilizing, which can harm your plants.

Sunlight Tolerance

Asters are particular about the weather and the amount of sunlight they get. In my experience, these plants prefer cool, moist summers under the full sun, though some of its hybrids prefer partial sun or a light shade.

They need at least 8 hours of sunlight daily, though some variants prefer less sunlight. While they prefer being under the sun, remember that too much sunlight will dry out their soil, negatively affecting the plant.

Contact your local garden centers or experts to confirm if your specific aster plant variant requires full or partial sun.

Propagating and Dividing

It’s beneficial to propagate asters because aster cuttings promote new growth and more blooming.

Asters usually grow into a large clump after an average of three years. When this happens, I suggest using a spade to divide the asters into groups, creating more space for growth.

This will not only prevent too much clumping from affecting the asters but also promote better airflow. Propagation guarantees that the flowers inherit the same species, color, and height as the original plant.

Purple aster flowers in black backgroundPurple aster flowers in black background

One way to propagate asters is to take 2 to 4 inches of cuttings from their stems, dip the cut end into a rooting hormone powder, and stick the cuttings into plastic pots with loose potting soil inside.

Monitor the cut flowers and stems and check whether clumping continues after dividing the aster plants. If you place asters into vases, note that their vase life will be around 5 to 10 days.

Common Aster Issues

While many asters are cold-hardy and typically grow well, they may still encounter problems due to improper care.

I’ll discuss some common issues and their solutions below.


Spacing is critical for aster plants to grow. When they aren’t appropriately spaced, they compete for nutrients and resources.

Crowded plants experience stunted growth due to the overcompetition and lack of resources. They’ll also become susceptible to fungal diseases, especially in crowded container gardens.

This is more apparent for larger Aster varieties since tall plants need even more space. Otherwise, they’ll wilt and slowly die.

Their flowers bloom less, and pruning becomes more difficult. Avoiding this problem is simple! Keep every aster plant at least 2 feet apart to give their roots space to breathe and grow into the earth.

NOTE: It’s best to prune asters after they’ve finished blooming. This deadheading will help them blossom during the next growing season.

Powdery Mildew

Powdery mildew in green leavesPowdery mildew in green leaves

Powdery mildew is a fungal infection that grows on the surface of aster leaves. These appear as white or gray patches, spreading over time and slowly affecting its growth.

These are some popular methods to combat powdery mildew:

  • Avoid getting your aster’s leaves wet. Focus only on watering its roots.
  • Clear out debris from the soil.
  • Remove any leaves showing powdery mildew immediately.
  • Apply fungicide every ten days or two weeks.
  • If the powdery mildew has spread, consider clearing the entire aster plant group surrounding or affected by it.


Yellow aphids on leavesYellow aphids on leaves

Aphids are small sap-sucking insects, often green in color. They pierce aster plants and extract necessary fluids, becoming a pest in larger gardens.

One way to remove aphids is to spray them directly with a water hose; however, intense pressure may be painful to the plant.

Instead, mix a few tablespoons of pure liquid soap with water and put it into a spray bottle. Apply the mixture directly onto the affected areas, especially underneath the leaves where there may be eggs.

Neem oil mixtures or water mixed with essential oil may also help.

Frequently Asked Questions

Next, I’ll cover common aster flower questions in this section.

How Much Mulching Do They Need?

I recommend a 2 to 3-inch mulch layer on top of the soil to retain moisture, prevent weeds, and regulate soil temperature.

What Do They Need to Survive Indoors?

Though asters are commonly outdoor plants, they can be grown indoors with bright indirect sunlight, well-draining soil, and enough moisture.

How Can They Benefit Your Garden?

Asters add a splash of vibrant color to your garden while attracting pollinators and adding diversity to your plants.


From my experience, growing a beautiful aster flower is easy if you regularly maintain its soil, water properly, and provide enough nutrients.

Check that there is proper moisture and monitor for clumping. After showing them lots of care and love, asters will reward your efforts with bright colors and beautiful star-like petals.


Other Guides from Planet Natural:

Cultivating a Healthy Zebra Plant — Quick Guide

How to Plant, Grow, and Care for Rosary Vine

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