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How to Plant, Grow, and Care for Hardy Asters

I have enjoyed gardening for at least 30 years and enjoy sharing my experience with others. Gardening is my time to meditate and unwind.

Aster amellus - (Botanika Zahrada Fata Morgana Praha)

Aster amellus - (Botanika Zahrada Fata Morgana Praha)

I fell in love with asters when I saw them growing alongside an entire town in Michigan. For some reason, I had trouble finding the plant. Then we moved, and the greenhouses in my new city had them in several colors.

Now I have purple, pink, and lavender hardy asters. The varieties I have will give me a treat in the fall when most of the other flowers are finished, but I always continue to look for other colors.

Another Name for Asters

Asters are also known as Michaelmas daisies. They do resemble daisies but are available in many more colors and bloom later. The plant was named in honor of the feast of St Michael, since they bloom at that time.

A rose-pink aster.

A rose-pink aster.

7 Reasons to Plant Asters

  1. They can be planted in both partial shade and full sun.
  2. They are low-maintenance plants and don't require a lot of water.
  3. The different varieties grow to be all different sizes. Some are only 12 inches tall. Others can grow up to 4 feet tall.
  4. Different colors are available. The most common color is lavender to purple. You can also find white, red, and pink.
  5. Butterflies and bees like them.
  6. The plants are hardy in all but the coldest regions of the US.
  7. Most varieties bloom later in the summer when most of the other perennials are finished.

Are Asters Perennials?

Hardy asters can be grown in most of the US, except for the coldest zones. They are hardy in Zones 3–9. Remember that there are hardy asters and asters that are annuals. The hardy asters will come back year after year, but the annuals will only last one year.

Always look at the description that comes with the plant. Then you won't be disappointed.

How to Plant Hardy Asters

  1. Choose a site with part to full sun.
  2. The area should be well-drained. Soil should have some humus.
  3. If planting from seed, they should be planted in the winter in pots. The seeds should be kept in the fridge for 4–6 weeks before planting. After this time, you can plant in pots 1 inch deep. Germination can be spotty. That is why I like to purchase the plants.
  4. The plants should be planted about 1–3 feet apart in a hole that is as deep as the pot. If the plants are root bound, gently tear part of the roots apart. This will encourage new root growth.
  5. I like to pour water directly into the hole that I created before placing the plant. Pat the soil around it.
  6. Mulch around the plant to retain moisture and keep away weeds.
Aster with beautiful fall color.

Aster with beautiful fall color.

Aster Plant Care Tips

1. Plants should receive 1 inch of water each week until established. Once they are growing well, they can tolerate drier conditions. Always water at the soil level so that leaves stay dry. The plants can be susceptible to powdery mildew if the leaves are wet.

2. Use a balanced fertilizer in the spring. Some gardeners recommend fertilizing every month and others just in the spring. The plants will grow too tall and flop if they get too much nitrogen. Whichever way you decide, give only a small amount at a time and leave a small space between the plant and where you apply.

3. Deadhead and you may get a second flush of bloom.

4. Once they are finished for the year, cut down and mulch to help protect them against a hard winter.

A lavender aster

A lavender aster

What Diseases Do Asters Get?


Powdery Mildew

This disease makes the leaves look white, almost like powder sugar was coated on them or milk left to dry It usually appears when the weather is hot and humid.

1. Give them plenty of room, so they can breathe and dry after rains. 2. Always water from the bottom of the plant, to keep the leaves dry. 3. Remove infected leaves. 4. Spray either with antiseptic mouth wash or use a fungicide. 5. Clean up all dead leaves in the fall and either burn or put in the garbage.

Root Rot

This is another disease caused by fungus. It can be caused by several different diseases. The problem is caused by planting in soil that is too wet, over-watering or having too much rain.The plants will appear stunted, wilted, and leaves will be discolored.

Sadly, this disease will usually kill the plant. Try to dry the soil around the plant by placing dry dirt around the base. Don't water again until the soil is completely dry. You can purchase chemicals to treat the problem, but since it can be caused by different fungal diseases, you should check with your local extension agent to find what disease it is first.

Tomato Spotted Wilt (Aster Spotted Yellows)

The disease is spread by leaf hoppers and turns the leaves yellow. It is a virus like disease caused by a phtoplasma. In place of blooms, there will be yellow bunches.

All plants with the disease will be lost. They will need to be removed from the garden and destroyed. If any weeds look like they have the disease, they will need to be destroyed also.

Butterflies like the asters too.

Butterflies like the asters too.

Insects That Bother the Plants

InsectDescriptionPossible Cure


Aphids are less than 1/4" in size and come in many different colors. They don't eat the plants, but rather suck on them and produce honeydew. Not only do they do harm this way, but the honeydew attracts ants which then spread other diseases to the plant. The insects will cause stunted growth and mutated leaves.

1. Wash the plants with water from the hose. This may remove the aphids from the plant. 2. Hand pick them off the plants if just a few. 3. Plant chives or onions in the area. They hate the smell. 4. Lady bugs will eat them. Some seed catalogs sell them.


These are also called Aster Leafhoppers even though they bother a large number of perennails. The insects migrate from the south and some eggs overwinter. If you have an infestation, you will see curled dried leaves or yellow leaves caused by lack of chlorophyll.

They like to land on green and dark surfaces. Protect the plants by using a straw mulch or place strips of aluminum around the plants. This confuses the leaf hoppers.


This insect looks like silvery gray scales on the stem of the plant. As an adult they look more like a diseased plant then an insect. You'll see a cottony egg sack. The insect sucks the juices from the plant. This will cause yellow leaves that drop.

Use neem oil. Mix 1 tablespoon with a quart of water. Spray plants with this mixture.

Spider Mites

These insects are so small that they are almost microscopic. You can identify them by the thick webs they spin on the plants. Leaves turn yellow and sometimes are more reddish or bronze. Spots will appear on the leaves and continue to spread.

Treat with neem oil. Mix one tablespoon to a quart of water. Spray the mixture so that it covers the entire plant.


These feed on the bottom of the leaves. They are so tiny, that they can be as small as 1/12." The flies are out during daylight hours, so sometimes you can see them flying around the plant. The flies produce honeydew which can attract ants. You will see wilting or yellow leaves and stunted growth.

1. Spray the leaves on the undersides and above with a spray from the hose to remove all of the insects that you can. 2. Use an insecticidal soap mixture and spray. 3. If you have a hand held vacuum, sweep up the insects. 4. If available place ladybugs in the garden. 5. Using reflective mulch can confuse the flies and they won't be able to find the plants.


You can grow asters from seed, but it is not recommended. If you want them to resemble the parent, you should divide them. If you'd like to try creating your own hybrid, go for it. Who knows, you could come up with a real winner and have fun in the process.

How to Propagate Asters

  1. Choose a large, well-established plant and cut out with a spade about 1/2 to 2/3 of it.
  2. Separate the portions you have dug and plant in a new spot.

That is all there is to it!

Favored Aster Varieties



Sky Blue


Crimson Brocade



Frikartiii (blooms early in July and blooms until first frost)



October Skies (very late blooming)

Sky Blue


Purple Dome

Dark Purple


More About Asters and Other Varieties

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2018 Barbara Badder


Barbara Badder (author) from USA on June 04, 2018:

Chitrangada, Thank your for your nice comments.

Chitrangada Sharan from New Delhi, India on June 04, 2018:

These flowers look lovely, and the colours are so bright. I liked the tabled information about the varieties, and the insects that may Brother the plants.

Thanks for sharing this wonderful information, with details.

Barbara Badder (author) from USA on June 03, 2018:

Your gardens sound wonderful. The house we are living in now only has room for container gardening for the vegetables. So I am not planting as many as I would like. Thanks for reading.

Frances Metcalfe from The Limousin, France on June 03, 2018:

Love asters. Am just beginning a new garden here in France, but we've concentrated our time making a veg plot complete with two polytunnels, but am looking forward to a cottage garden at the front and asters would be perfect. Lovely article.

Barbara Badder (author) from USA on June 02, 2018:

Thanks. I am going to try both seeding and dividing.

agusfanani from Indonesia on June 02, 2018:

Asters are very beautiful flowers and I think they are not so difficult to be propagated.

Barbara Badder (author) from USA on June 02, 2018:

Thanks Peggy for commenting. I am sorry that you are missing out on so many perennials your had in the past. You'll need to write about what you can grow in Houston, so we can learn about those plants.

Barbara Badder (author) from USA on June 02, 2018:

Thanks Linda. I am happy you could use the information.

Peggy Woods from Houston, Texas on June 02, 2018:

Since the asters do not enjoy hot and humid weather I'll have to pass on planting them here in Houston. They are beautiful flowering plants and I remember them in some of the gardens when I lived in Wisconsin many years ago. Good article!

Linda Crampton from British Columbia, Canada on June 01, 2018:

I love asters. Thanks for sharing all the information. I found the tables about diseases and insects especially useful.

Barbara Badder (author) from USA on June 01, 2018:

Mary, We have too much shade here too. I have a couple of good spots though and I do love asters. I've planted two varieties

Mary Norton from Ontario, Canada on June 01, 2018:

I have not considered asters but will do so now as with so many trees, we have mostly shade. Thanks for the reminder on this beautiful plant.