How to Plant, Grow, and Care for Hardy Asters
I fell in love with asters when I saw them growing along an entire town in Michigan. For some reason, I had trouble finding the plants. Then we moved and the greenhouses here had them in several colors.
Now I have purple, pink and lavender asters. The varieties that I have will give me a treat in the fall when most of the other flowers are finished. I'll continue to look for the other colors.
About the Plant
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.
Reasons to Plant
- They can be planted in both partial shade and full sun.
- They are low maintenance plants and don't require a lot of water.
- The different varieties grow to be different sizes. Some are only 12" tall. Others can grow up to 4'.
- Different colors are available. The most common color is lavender to purple. You can also find white, red, and pink.
- Butterflies and bees like them.
- The plants are hardy in all but the coldest regions of the US.
- Most varieties bloom later in the summer, when most of the other perennials are finished.
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
- Choose a site with part to full sun.
- The area should be well drained. Soil should have some humus.
- 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 prior to planting. After this time, you can plant in pots 1" deep. Germination can be spotty. That is why I like to purchase the plants.
- The plants should be planted about 1 to 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.
- I like to pour water directly in the hole that I created before placing the plant. Pat the soil around it.
- Mulch around the plant to retain moisture and keep away weeds.
How to Care for Asters
1. Plants should receive 1" 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.
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.
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.
Insects That Bother the Plants
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.
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 Divide:
- Choose a large well established plant and cut out with a spade about 1/2 to 2/3 of it.
- Separate the portions that you have dug and plant in a new spot.
That is all there is to it.
Some Good Varieties
Frikartiii (blooms early in July and blooms until first frost)
October Skies (very late blooming)