Crooked Stem Aster is a perennial flower native to Eastern North America. Scientifically known as Symphyotrichum prenanthoides, it will grow between 1-4′ tall in partial shade to full sun. Blooming purple flowers for 4 weeks in Autumn, it supports numerous specialty bees and other pollinators blooming in Autumn from September to October.
In this article:
- What is Crooked Stem Aster
- What are the benefits of Crooked Stem Aster
- How to grow and care for Crooked Stem Aster
- Identification / Characteristics
- What Wildlife, Pests, and Diseases effect Crooked Stem Aster
- Where to buy Crooked Stem Aster
- Uses of Crooked Stem Aster
- Final thoughts
What is Crooked Stem Aster
A native wildflower found along woodland edges, in open woods, and streams, Crooked Stem Aster is a lovely addition to the Autumn landscape. Blooming purple to blue flowers in Fall, it provides crucial nectar for pollinators and specialty bees. You can find naturally occurring in open woods, along streams, and along woodland borders.
It’s common name, ‘Crooked Stem Aster’ refers to the nature of it’s stalk. At each junction of the stalk, the stem will bend forming a large angle as it ascends. Because of this it is also sometimes referred to as Zig-Zag Aster.
A highly adaptable plant, it will form a dense flowering mound in full sun, while more sparse flowering will occur in shadier locations. I’ve noted this plant on slopes at the woodland border and along woodland streams where it receives partial shade. Take heed though, it will spread via Rhizomes, so should you grow this in your yard, place it somewhere where it has room to spread or ample competition is present.
Native Range of Crooked Stem Aster
The native range of Crooked Stem Aster is primarily Iowa to Minnesota/Wisconsin/Ontario, East to New York and North Carolina. Isolated populations have been found in Tennessee, Georgia, South Carolina, and Indiana. In Canada this plant is threatened or endangered. 
Crooked Stem Aster Reference Table
|Scientific Name||Symphyotrichum prenanthoides|
|Common Name(s)||Crooked Stem Aster, Zig-zag Aster|
|Native Range, USDA Zone||Eastern North America. USDA hardiness zones 4-7.|
|Bloom Duration, Color||4 weeks, Blue/purple/lavender|
|Spacing / Spread||1-2′|
|Light Requirements||Partial sun to Full sun|
|Soil Types||Sandy loam to clay loam|
|Moisture||Moist to medium moist, well-drained|
|Fauna Associations / Larval Hosts||Bees|
What are the Benefits of Crooked Stem Aster
Mass plantings of Crooked Stem Aster can be valuable nectar and pollen source for bees and butterflies late in the season. Depending on sunlight conditions, blooming can start in August or October, meaning this plant can be an important Fall food source.
Grow and Care for Crooked Stem Aster
The natural habitat of Crooked Stem Aster is along the bank of streams and creeks. All the pictures you see in this article were taken along a creek behind my home. Creek banks provide great habitat for this plant, as they are generally shaded yet provide moist sandy soil that drains well.
For sunlight, Crooked Stem Aster will grow best and flower the most in full sun. It will readily tolerate partial shade though.
Crooked Stem Aster will grow well in soils ranging from sandy loam to clay loam. It will benefit from having a decent amount of organic matter present in the soil.
Crooked Stem Aster prefers moist loamy soil. The key factor is that the soil drains well.
The primary maintenance for Crooked Stem Aster would be to keep it in check. If the self-seeding or rhizome spreading gets out of hand, you may need to remove seedlings or mature plants. You should be able to divide Crooked Stem Aster in Spring.
But, like many Asters, Crooked Stem Aster can sometimes become top-heavy and flop over. To help prevent this, give it a the Chelsea Chop in June to reduce the overall height. Don’t be scared! It won’t hurt the plant.
Crooked Stem Aster can be cosmetically effected by a variety of fungi such as rust, leaf spot, and mildew. Should the plant be grown in constantly moist soil that doesn’t drain, the plant will likely die of root or stem rot fungi. So, plant it in well-draining soil!
How to Grow Crooked Stem Aster from Seed
Like many Asters, Crooked Stem Aster should be cold stratified for 30-60 days in the fridge before sowing, or it could be Winter Sown. Seeds should be scattered and pressed into the soil, and not buried. Keep the soil moist, but not wet, and place the container in a location that receives morning sun and afternoon shade.
Identification and Characteristics of Crooked Stem Aster
The overall plant grows 8″-36″ and is erect. Naturally found around creeks, moist open woodlands and forest borders.
The stalk is erect and covered with tiny white hairs. It is bent sharply at nodes, primarily in the upper portions of the plant. Older plants may produce multiple stalks. 
Crooked Stem Aster leaves are simple, alternate, oblanceolate with serrated margins, and 1/2-3″ long by half as wide. There is a prominent central vein adn the leaf will clasp to the stem, similar to New England Aster. 
Small daisy like blue to purple blooms occur in Autumn. Flowers are foughly 1/2″ diameter (12 mm) and will have 15-30 rays (petals) and 40-65 disc flowers that begin as yellow, and change to purple or brown as the flower ages. 
The amount of flowering will be dependent on the light conditions. Sunnier locations will produce more blooms.
Several weeks after flowering seed heads will form. Individual seeds are similar to other asters in that they will be attached to the central disc, and have a small feather tail to help it be distributed via wind.
To save seed from Crooked Stem Aster, return to the plant several weeks after flowering has finished. Bring a paper bag, and simply pinch the feathers on the seed head and pull. Then place the seed (with feathers attached) in the brown paper bag.
The short video takes you through the entire process. In the video they use New England Aster as the subject, but the process is identical.
Allow the paper bag to dry in a cool dark place out of the sun for a week or two, or until you are satisfied the seed is dry. Then store it in a sealed plastic container for up to two or three years.
The root system is fibrous with elongated rhizomes. This plant will spread via rhizomes. 
Wildlife, Pests, and Diseases associated with Crooked Stem Aster
Numerous bees feed on the nectar pollen, while butterflies will visit for nectar. There are several insects that will eat the foliage such as Silvery Checkerspot.
Turkey and other game birds will eat the seeds of Asters late in Fall. And other herbivores will sometimes eat the seeds and foliage. Birds also use the previous year’s foliage in nesting material in Spring. 
Deer and Rabbits
Young foliage can be browsed by deer and rabbits.
Where you can buy Crooked Stem Aster
Crooked Stem Aster is not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.
Where to buy seeds
We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)
Uses of Crooked Stem Aster
Crooked Stem Aster could be a somewhat showy flower to have along a woodland border providing beautiful Autumn blooms. It tends to bloom later than many other Asters, with it’s blooming period overlapping with Aromatic Aster (the last blooming Aster). The wild nature of Crooked Stem Aster also means it could be a good choice for naturalizing a recently cleared area or habitat restoration.
It would not be a good choice for a small flower bed or garden, as it’s ability to spread via rhizomes means that it likely will become aggressive, possibly overtaking the bed.
For companion plants, shorter late blooming perennials would be best. The main factors to consider when selecting companion plants would be moisture loving, partial shade tolerant perennials. White Turtlehead and Ironweed would be good candidates to grow near Crooked Stem Asters.
The Iroquois Tribe had several uses for Crooked Stem Aster. A decoction of roots was used to treat kidney problems or colds in adults, and to help babies with fevers. [na]
Crooked Stem Aster is one of the many Aster flowers one could encounter on an Autumn hike with friends and family (that’s how I found it). It is a beautiful flower and not too tall.
However, for most people it is better suited to wild gardens, micro-prairies or the creeks and forests it naturally inhabits rather than the formal flower beds. As like many Asters, it can become a bit aggressive.
 – Crooked Stem Aster. USDA. Accessed 07SEP2022.
 – Nesom, G.L.. “Symphyotrichum prenanthoides”, Plant Fact Sheet, USDA NRCS, 2009. Retrieved 07SEP2022. https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mdpmcfs9054.pdf
 – Zhang, J.J., D.E. Stephenson, J.C. Semple and M.J. Oldham. 1999. COSEWIC status report on the crooked-stem aster Symphyotrichum prenanthoides in Canada, in COSEWIC assessment and status on report on the crooked-stem aster Symphyotrichum prenanthoides in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-16 pp.
 – Clark, Larry, and J. Russell Mason. “Olfactory discrimination of plant volatiles by the European starling.” Animal Behaviour 35.1 (1987): 227-235.
 – ‘Crooked Stem Aster‘, North American Ethnobotany Database. Accessed 08SEP2022.
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