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Growing Asters
How to Plant, Grow, and Care for Aster Flowers
How to Plant, Grow, and Care for Aster Flowers
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Asters are daisy-like perennials with starry-shaped flower heads. They bring delightful color to the garden in late summer and autumn when many of your other summer blooms may be fading.
There are many species and varieties of asters, so the plant’s height can range from 8 inches to 8 feet, depending on the type. You can find an aster for almost any garden at garden centers in autumn!
The plant can be used in many places, such as in borders, rock gardens, or wildflower gardens. Asters also attract bees and butterflies, providing the pollinators with an important late-season supply of nectar.
Planting
Choosing and Preparing a Planting Site
- Asters prefer climates with cool, moist summers—especially cool night temperatures. In warmer climates, plant asters in areas that avoid the hot mid-day sun.
- Select a site with full to partial sun.
- Soil should be moist but well-drained, and loamy.
- Mix compost into the soil prior to planting. (Learn more about soil amendments and preparing soil for planting.)
Planting Asters
- While asters can be grown from seed, germination can be uneven. You can start the seeds indoors during the winter by sowing seeds in pots or flats and keeping them in the refrigerator for 4 to 6 weeks to simulate winter dormancy. Sow seeds one inch deep. After 4 to 6 weeks, put the seeds in a sunny spot in your home. Plant outside after the danger of frost has passed. (See local frost dates.)
- The best time to plant young asters is in mid- to late spring. Fully-grown, potted asters may be planted as soon as they become available in your area.
- Space asters 1 to 3 feet apart, depending on the type and how large it’s expected to get.
- Give plants plenty of water at the time of planting.
- Add mulch after planting to keep soil cool and prevent weeds.
Asters are highly attractive to pollinators, especially bees and butterflies.
Care
How to Grow Asters
- Add a thin layer of compost (or a portion of balanced fertilizer) with a 2–inch layer of mulch around the plants every spring to encourage vigorous growth.
- If you receive less than 1 inch of rain a week, remember to water your plants regularly during the summer. However, many asters are moisture-sensitive; if your plants have too much moisture or too little moisture, they will often lose their lower foliage or not flower well. Keep an eye out for any stressed plants and try a different watering method if your plants are losing flowers.
- Stake the tall varieties in order to keep them from falling over.
- Pinch back asters once or twice in the early summer to promote bushier growth and more blooms. Don’t worry, they can take it!
- Cut asters back in winter after the foliage has died, or leave them through the winter to add some off-season interest to your garden.
- Note: Aster flowers that are allowed to mature fully may reseed themselves, but resulting asters may not bloom true.
- Divide every 2 to 3 years in the spring to maintain your plant’s vigor and flower quality.
Pests/Diseases
Susceptible to:
- Powdery mildew
- Rusts
- White smut
- Leaf spots
- Stem cankers
- Aphids
- Tarsonemid mites
- Slugs and snails
- Nematodes
Harvest/Storage
- Asters work well as cut flowers! Here’s how to cut and keep flowers fresh.
Recommended Varieties
The most common asters available in North America are the New England aster (Symphyotrichum novae-angliae) and the New York aster (Symphyotrichum novi-belgii). Both of these plants are native to North America and are great flowers for pollinators. We recommend planting a native species of aster over a non-native species when possible.
North American Asters
- New England asters (S. novae-angliae): Varieties have a range of flower colors, from magenta to deep purple. They typically grow larger than New York asters, though some varieties are on the smaller side.
- New York asters (S. novi-belgii): There are many, many varieties of New York asters available. Their flowers range from bright pink to bluish-purple and may be double, semi-double, or single.
- Blue wood aster (S. cordifolium): Bushy with small, blue-to-white flowers.
- Heath aster (S. ericoides): A low-growing ground cover (similar to creeping phlox) with small, white flowers.
- Smooth aster (S. laeve): A tall, upright aster with small, lavender flowers.
European/Eurasian Asters
- Frikart’s aster (Aster x frikartii) ‘Mönch’: Hailing from Switzerland, this mid-sized aster has large, lilac-blue flowers.
- Rhone aster (A. sedifolius) ‘Nanus’: This aster is known for its small, star-shaped, lilac-blue flowers and compact growth.
Wit & Wisdom
- Asters, one of September’s birth flowers, were once burned to ward off serpents.
- The name “aster” comes from the Ancient Greek word for “star”—a reference to the plant’s star-shaped flowers.
- Thanks to the aster’s late bloom time, they are sometimes called “Michaelmas daisies.” Michaelmas is a holiday that occurs annually on September 29.
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Reader Comments
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Growing asters
Help
We just had a couple of unusually hot days for Ohio.My potted Aster just lost the majority of its blooms.They turned brown and shireveld up.Kinda was hoping to plant this one soon,but now unsure
asters getting to big
My NE Aster is getting bigger around every year- and starting to take over the patch- crowding out other perennials in my full-sun garden in west-central Illinois. What can I do?
My Aster is taking over my flower bed how do I stop this from ha
Aster taking over my flowers
Treating Morris Lace bug Eggs with Sevin?
My Purple Dome Asters did beautifully when first planted in the summer of 2017 in Indianapolis, Indiana. But last summer, they were covered with what I think were these lace bugs. We drenched them with Neem Oil all summer and it did not help at all!!! My online research says to look for the emerging eggs in late April or early May. My landscaper says to spray the tender plants with Sevin. Is this advisable? If not, what to do?? The bug was about 1/8”, grey, and with a body shape sort of like a very tiny Japanese beetle. Need help quickly!
for bees
What asters do you suggest for bees in Piedmont NC? They will be planted on fallow land and left untended.
transplanting
when is the best time to relocate asters? I have two that have out grown their current location and need to be moved. I was thinking of locating them after they have finished blooming this fall.
When Should Asters be Planted
I live in Glastonbury, CT 06033
What time of year should Asters be planted?
Are they perennials?
Thanks,
Asters
See the Planting section, above, for the answers!
Giant asters
I have asters that I swear have multiplied and have become so giant over the last few years that we are becoming overtaken. Should I be cutting them back until the 4th of July like I've heard you should do with mums? I've had them for a handful of years and I can't remember them ever looking this wild.
Pruning Asters
If excessive height is the problem, then you should pinch back the young shoots to encourage the plants to become bushier. If they are simply too big all-around, you can cut them back by about half up until the beginning of July (the 4th of July, essentially). Don’t wait any longer than that, though, as it could result in delayed flowering.
Asters
My asters were lovely last year but cannot see any buds yet 14/9/17. Will they flower this year?
asters did not bloom
Asters are pretty forgiving plants. Are you sure you don’t have a biennial variety? Asters bloom best in full sun but tolerate part shade. They do not like to sit in water, so well draining soil is important, and good quality—loamy or composted—soil helps. Next year, add a shovelful of compost at the base in spring.
Aster grown control
I have heard that aster can grow to be too large of a bush. I live in SE Pa and would like to grow it in a pot, maybe planted into the ground with the bottom torn open a bit to control its growth. Is that advisable? And would that control it from getting too tall and large?
aster control
You can grow asters of varying sizes; choose what you want. You could plant it in a pot and put the pot into the soil to control it. If the plant is cramped in the pot, it may become cramped (leggy or some other manifestation of stunted growth) but you should go to or contact a plant vendor and talk to them with the goal of purchasing a plant that will perform in the way you want it to.
Asters
I live in zone 6 and have been looking for hardy perennials that can handle full sun.
I just purchased some beautiful asters and am concerned because it gets hot here and above it says cool, moist summers and right now it's hot and dry.
Any planting tips that can help me ensute they can thrive in spite of the heat?
Thanks; all help will be very much appreciated.
Weird things are growing near my aster powder puffs
I bought aster powder puff seeds and they've grown to be about one inch tall. They're still very young but there are white-orange round things that are growing as well and I'm very concerned. Also, their are bites on the leafs and I don't know how to get rid of whatever that's eating the leafs. Please help!! Thank you!
aster rust
It sounds like your asters have a rust disease. You should remove all of the leaves that are infected and the entire plant if all of the leaves have rust.
Plant in pot or ground?
I just bought 2 aster plants that I'd like to plant in 2 pots I have on my front porch (full sun). I'm in zone 5b and am wondering what my options are. Is it best to plant the asters in the pots, then bring the pots in and keep them over the winter to plant in my garden in the summer, or put them in pots now and then plant them in my garden after they've finished blooming this fall? Thanks!
Potted Asters
You can either leave them in the pots outside (do not bring them in) and plant them in the early spring or go ahead and plant them now, but do it soon, as night temperatures are dropping fast! Either way, they require a cold dormancy period so they must stay outside.
aster died after a month.
This is the first time i had them. I water them every other day and they started to turn brown. So just water them twice a week and they still turn brown on me. Now they all died. What did i do wrong. And i even mulch them.
Watering Asters
Hi Donna,
I suspect they died from overwatering. I suggest starting over with new plants. Water them when you plant them, and then wait until they dry out a bit before giving them a good soaking. Plants like less-frequent, deep watering. Also, pay attention to the weather and the moisture level of the soil. Some weeks you will water more, others less. Air temperature and rainfall really determine how much water your plants need from week to week.
So I decided to give planting
So I decided to give planting a shot and I bought Aster seeds.. I had no idea how to plant, actually I have no knowledge about planting at all .. Anyway I followed my instinct and prepared the soil, I actually mixed a 2/3 soil with 1/3 compost and watered it a little, then I picked the seeds and pushed them into it, but not so deep .. After I finished I wateredthe soil well and positioned it in a full sunny spot ..
Then I thought why I haven't google it, so I did .. And here it's, all the results are talking about 6 - 8 weeks in the refrigerator, and I just got confused ..
I need to know if my seeds are going to grow, or at least if theres anything I can do now !
P.S. I'm watering it twice a day
Hi Dana,
Hi Dana,
Do not overwater. Just keep the soil moist. Use a spray bottle so that you don’t disturb the seeds too much. We suggest that you cover the pots or trays with plastic. This will keep the soil moist so that you don’t need to water. You should see new growth after about 10 days. When the seedlings emerge remove the plastic and mist the soil lightly. Put the plants in your sunniest window. When the seedlings have their first leaves transplant into bigger individual pots.
Asters
I have a large aster plant in my new yard. It dried out and fell over this winter. Should I cut it to the ground?
Yes, you can cut off the
Yes, you can cut off the dried out dead branches. This is normal for asters. As soon as the weather warms up you should see some new growth from the bottom of the plant.
My Asters are turning brown
I just bought a pot of asters a week ago and the leaves started turning brown from bottom up. At first, I watered every 2 days. When they start wilting, I asked the seller about it and he said to water everyday. So I watered every night. But it's not helping. Need help urgently. Really don't want the Asters to die. Or I at least want them to last till the Chinese New Year. Thanks in advance.
Asters grow best in full sun
Asters grow best in full sun and in moist well-draining soil. Make sure the soil is not too wet. Please see our planting and care tips at the top of this page.
Aster that won't bloom
I have many aster plants that bloom beautifully. However, at one site, there's a lush, green aster with many little buds on it, but for the second year, the plant doesn't flower. It's planted in full sun, doesn't get chemical fertilizer, and is watered somewhat every few days. The soil seems to be decent loam. Why won't this little guy bloom???
If the plants foliage looks
If the plants foliage looks nice with no signs of insects or yellowing keep the plants moist and do not fertilize. Add some mulch around the plant to keep the soil cool and moist. Hopefully the cooler weather will produce some flowers for you.
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