Frost Aster is a common Fall flower to grace seemingly every roadside ditch or any piece of unattended ground in Eastern North America. Scientifically known as Symphyotrichum pilosum, it grows up to 3′ tall in full sun and well-draining soil. Blooming numerous small white daisy-like flowers for six weeks in Autumn, it attracts bees & butterflies.
In this article:
- What is Frost Aster
- What are the pros & cons of Frost Aster
- How to grow and care for Frost Aster
- Identification / Characteristics
- What Wildlife, Pests, and Diseases effect Frost Aster
- Where to buy Frost Aster
- Uses of Frost Aster
- Final thoughts
What is Frost Aster
Frost Aster is one of the later blooming Fall Flowers that graces Eastern North America. A herbaceous perennial, it will die back to ground at Winter only to reemerge in Spring. But you can know where this plant after the growing season as it will have a set of basal leaves that will persist all winter long.
The scientific / Latin name of Frost Aster is Symphyotrichum pilosum, which is important to remember as this plant goes by many common names. The many common names can add even more confusion, as several of them are shared by multiple species of White Aster such as ‘Heath Aster’ (Symphyotrichum ericoides), ‘Calico Aster’ (Symphyotrichum lateriflorum), and Panicled Aster (Symphyotrichum lanceolatum). All of these aforementioned species look similar at a glance in that they bloom small white daisy-like flowers. Further complicating their identification is that their blooming periods and habitats all overlap! (Jump to Identification)
Of the ‘white’ asters, Frost Aster is probably one of the showiest in that it will produce numerous small white daisy-like flowers that can really give a garden a splash of white in Autumn. In this way it quite important to local wildlife as it is an excellent nectar and pollen source for dozens of species of bees, butterflies, wasps, flies, and other pollinators. Additionally it will host several butterflies and moths, while the seeds are eaten by mice, Grouse, Turkey, and Sparrows. Young tender foliage is also browsed by deer and rabbits, further increasing it’s value to wildlife.
Frost Aster readily pops up in vacant lots, fields, ditches, or anywhere there is bare soil via aggressive self-seeding. In this manner it is not always a great choice for formal flowerbeds, but can be a great addition to wildflower meadows or perennial borders to add some late-season blooms. If you are unsure of whether you wish to plant it, well I have good news – it may just find you (as it did me)!
Native Range of Frost Aster
The native range of Frost Aster is Eastern North America, east of the Rocky Mountains. It’s range is basically everything east of an imaginary line from Texas to South Dakota & Ontario.
That natural habitat of Frost Aster is dry to medium-moist sites in full sun to partial shade such as the forest edge, meadows, prairies, or open woodlands. It is a highly adaptable and aggressive native plant that is common throughout Eastern North America. It can seemingly grow anywhere there is disturbed or bare soil similar to dandelions – vacant lots, sidewalk cracks, even in the cracks of a bridge! 
Frost Aster Reference Table
|Scientific Name||Symphyotrichum pilosum, Aster pilosus|
|Common Name(s)||Frost Aster, Oldfield Aster, Hairy White Oldfield Aster, Awl Aster, Hairy Aster,|
|Native Range, USDA Zone||Eastern North America, USDA Hardiness Zones 4-8|
|Bloom Duration, Color||6 weeks, White|
|Height||2-3′ (60-90 cm)|
|Spacing / Spread||2-4′ (60-120 cm)|
|Light Requirements||Full sun to partial shade|
|Soil Types||Sandy loam, clay loam, rocky soil|
|Moisture||Medium-moist to dry locations|
|Fauna Associations / Larval Hosts||Numerous pollinators visit for nectar and pollen. Hosts several butterflies (jump to pollinator section)|
Pros and Cons of Frost Aster
Of the late blooming White colored Asters, Frost Aster is one of the showiest producing dozens of white flowers. It’s prolific blooming can make it stand out compared to contemporary white Asters
The large numbers of blooms means that it can feed many pollinators. And it does. There are numerous species of bees, wasps, and pollinating flies that will visit this plant to obtain pollen or nectar. In addition to pollen and nectar there are many types of insect that feed on the foliage, from larvae of the Pearl Crescent to grass hoppers, beetles, and moths.
This plant can grow seemingly anywhere that has well drained soil. And I mean anywhere. It’s been documented popping up in abandoned fields, flowerbeds, along sidewalks, ditches, and even in the cracks of bridges! When it comes to ‘strange places to grow’, Frost Aster can compete with dandelions!
The numerous flowerheads also produce numerous seeds that are more than happy to germinate in any patch of bare or disturbed soil. This makes Frost Aster one of the more aggressive self-seeding native plants around. If you garden long enough, you will likely encounter this popping up in unwanted places. In fact this plant has been listed as invasive in several other countries. 
Flopping / Leaning
If allowed to grow, the many flowerheads can make the plant top heavy and prone to leaning. To counteract this, or reduce the effect, it is recommended that you give it the Chelsea Chop earlier in the season, by late June/July.
Late season leaf damage
If exposed to drought, the lower leaves along the stem will likely turn brown and crispy, detracting from it’s appearance. Now, this isn’t that big of a deal in a wildflower or prairie situation, but if it is isolated it will be noticeable.
Grow and Care for Frost Aster
For sunlight requirements, Frost Aster will grow best and prefer full sun conditions, which is at least six hours per day. It can however tolerate and look good in partial shade, which is 4-6 hours per day. In general, the amount of showiness or blooms will be increase with the amount of sun it receives. 
Frost Aster is highly adaptable for soil types, being able to grow in sandy loam to clay loam or even rocky/gravely areas. The fact that this plant pops up almost anywhere speaks to it’s adaptability.
For moisture, Frost Aster grows best in dry to medium-moist soils. It doesn’t do well in moist or wet soil.
The two primary chores with Frost Aster are performing the Chelsea Chop in late Spring to early Summer, and pulling unwanted seedlings.
Frost Aster does not need supplemental fertilizer.
How to Grow Frost Aster from Seed
Frost Aster is an interesting seed in that it needs exposure to sunlight to germinate, but can be readily germinated without stratification once the temperatures reach a certain threshold and it is exposed to sunlight.
The seed can achieve a 50% germination rate once seed is incubated at 25C (75F) & exposed to light, and upwards of 90% once temperatures reached 35C (95F). But, if allowed 12 weeks cold stratification before sowing in exposed light, the germination rates were found to be quite high even at lower temperatures of 10C (50F), and over 95% at 25C (75F). [Baskin 1979] So, if you want to get an early start and a high germination rate, you should be cold-moist stratifying the seed or Winter Sowing. See references 
Process to grow Frost Aster from seed
The following steps assume you are either Winter Sowing the seed, or planting in very early Spring. (See our guide to Winter Sowing here)
- Fill a suitable container with moist potting soil. Tamp the soil firmly.
- Scatter approximately 5 seeds on the soil surface. Press the seeds into the soil, taking care not to bury them.
- Place the container in a location that receives morning sun and afternoon shade.
- Keep the container moist by misting it with a spray bottle or pump sprayer. Do not use a large watering can, as the tiny seeds can wash away.
- Germination should occur once outdoor temperatures reach 75F during the day for unstratified seed. If winter sown or cold stratified before sowing, germination can occur much sooner when outdoor temperatures reach 50F.
Time to establish
Frost Aster should bloom the first year if there are sufficient nutrients available and the seeds germinate in early Spring. If extremely poor conditions, it may only form a basal rosette of leaves for the first year, but will bolt the second. 
Identification and Characteristics of Frost Aster
Identification of Frost Aster can be difficult due to similarities of other small-flowered white Asters. However, particular attention should be paid to the number of petals (ray flowers), and if basal leaves are present.
Frost Aster will typically grow 2-3′ tall (60-90 cm) if allowed to grow to full size. But many plants one may encounter along roadsides or abandoned areas, vacant lots will often be shorter as this plant is often considered a weed and is often mowed or trimmed with a string-trimmer. But, if full size it will often arch over due to the weight of the flowerheads.
In general Frost Aster will be erect, growing 3′ tall with branching at the upper half of the stem. Young stems are green with white hairs while lower, older stems are brown or reddish brown and hairless. The base of the stem is often woody. 
Leaves along the stalk are alternate, up to 4″ long by 3/4″ wide and lanceolate elliptic in shape, with several teeth along the edges (but sometimes toothless). If examined very closely, you can see the margins are ciliate. The leaves generally have no stems (sessile) and have few hairs on the upper surface, while the lower surface will have more hairs. Frequently in the upper portion of the plant you will encounter secondary leaves or leaflets that have similar characteristics, but are much smaller. 
The base of the plant will have basal leaves that are 3″ long and up to 1″ wide. They generally persist throughout Winter, but may not be present in hot summers. Basal leaf shape will be oblanceolate or elliptic in shape, and have smooth margins.
Upper stems will turn into panicles of flowers that reach up to 1-2′ long. Individual flowers are up to 1-1/4″ diameter and are daisy like. Similar to other Asters, there will be both disc and ray flowers present. There will generally be 15-30 petals (ray flowers) that will be white in color while disc flowers are yellow, and change to a reddish color after pollination (similar to Shorts Aster).
How to save seed
To save seed from Frost Aster, about 4 weeks after blooming seeds will form on the flowerheads. There will be a seed in the center of the disc with a small feather attached giving a fuzzy appearance. To collect/harvest the seed, simply cut the flower heads off and place them into a paper bag or just pluck the feathers from the flower heads and place them into a bag.
Store the seed with feathers attached in a breathable container (like a paper bag) for a week or so in a cool dry place to ensure the seed is fully dry. Then, store the seed in a sealed container in the fridge (for maximum longevity) before winter sowing or cold-moist stratification, or in an envelope in a cool dry place until ready to sow.
The root system of Frost Aster is a branching caudex that produces fibrous roots and short rhizomes. Although this plant makes rhizome roots, they don’t run far like aggressive spreaders such as Canadian Goldenrod. Instead, they will form tighter colonies. The primary method this plant spreads is via self-seeding.
Wildlife, Pests, and Diseases associated with Frost Aster
The ease at which pollinators can get nectar and pollen mean this plant is attractive to almost any species of bee, and has been well documented. Charles Robertson in his amazing 1929 book documented over 90 bee species visiting Frost Aster. Also, over 70 species of flies were recorded visiting this plant .
This plant will be visited occasionally by butterflies. But in general, bees prefer the white aster flowers while butterflies and moths prefer purple Aster species such as New England Aster and Smooth Blue Aster. 
In addition to pollinators, there are numerous insects that will feed on the foliage. Caterpillars of the Pearl Crescent butterfly, and several other insects
Deer and Rabbits
Like many Asters, deer and rabbits will browse young tender foliage. As the plant ages, they won’t eat the mature parts. This may be due to the leaves and stems becoming somewhat rougher, but this is just my speculation. None the less, one should protect young seedlings with Liquid Fence to protect them if you are concerned with herbivore pressure.
This plant can be susceptible to late season foliar disease such as rust.  However, by this point the flowers are showing brightly, and the leaves, even if diseased are somewhat inconspicuous and small. So, any leaf spot or powdery mildew won’t have a much of an effect on the overall appearance.
Where you can buy Frost Aster
Frost 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 Frost Aster
Frost Aster is a versatile plant for the wildflower garden, meadow, micro-prairie, or perennial border garden. The fact that it doesn’t have large leaf mass means that it is less likely to shade out other plants, and can grow in a high competition environment.
It’s aggressiveness in self-seeding though mean that it probably is not a good choice for a formal flowerbed, despite it’s wildlife value. One should be cautious where you allow it to grow, and be aware that it is possible for a seedbank to develop.
Frost Aster is so adaptable that it can grow well with many other plants. Some obvious choices would include other Fall Asters such as Aromatic Aster (which I know it does well with), Spotted Bee Balm, Mountain Mints, and Showy Aster. It also looks nice planted among prairie grasses such as Side Oates Grama, Prairie Dropseed, Purple Love Grass, or Pink Muhly Grass.
Medicinal Uses of Frost Aster
I could find no references to medicinal uses nor toxicology of Frost Aster. No records were found.
Frost Aster is really makes a pretty floral display late in Autumn and it’s white color blends well with any other flower. While most of your neighbors will be putting their gardens to bed for the year, yours will still be blooming and attracting bees serving as a valuable food source.
The only real drawback is how aggressive it is in a formal mulched flower bed. It self-seeds enough to make it a nuisance in a well-manicured garden. But it is right at home and looks good in a wildflower area whether erect or leaning over. That being said, it has it’s place, and as long as you don’t try to force it to grow in a traditional mulched garden it will look just fine.
Find more native plants here
 – Bryson, Charles T., and Michael S. DeFelice, eds. Weeds of the South. University of Georgia Press, 2009.
[gen desc][non toxic]
 – Hairy White Oldfield Aster. USDA NRCS. Accessed 12OCT2022. https://plants.usda.gov/home/plantProfile?symbol=SYPIP3
[larval host pearl crescent & sidewalk] – Kenneth D. Frank. Ecology Center Of Philadelphia, Fitler Square Press, 2015, pp.387.
[big stratify] – Baskin, Jerry M., and Carol C. Baskin. “The germination strategy of oldfield aster (Aster pilosus).” American Journal of Botany 66.1 (1979): 1-5.
[germinate] – Baskin, J. M., and C. C. Baskin. “The Light Requirement for Germination of Aster Pilosus Seeds: Temporal Aspects and Ecological Consequences.” Journal of Ecology, vol. 73, no. 3, 1985, pp. 765–73. JSTOR, https://doi.org/10.2307/2260145. Accessed 13 Oct. 2022.
[stratification] – Kajbaf, Kimia. Identification of an Unknown Missouri glade aster. Diss. Southern Illinois University at Edwardsville, 2015.
[flies] – Tooker, John F., Martin Hauser, and Lawrence M. Hanks. “Floral host plants of Syrphidae and Tachinidae (Diptera) of central Illinois.” Annals of the Entomological Society of America 99.1 (2006): 96-112.
[robertson] – Robertson, Charles. “Flowers and insects; lists of visitors of four hundred and fifty-three flowers.” (1928).
[90bees] – Marlin, John C., and Wallace E. LaBerge. “The native bee fauna of Carlinville, Illinois, revisited after 75 years: a case for persistence.” Conservation Ecology 5.1 (2001). Accessed 12OCT2022
 – Tooker, John F., Martin Hauser, and Lawrence M. Hanks. “Floral host plants of Syrphidae and Tachinidae (Diptera) of central Illinois.” Annals of the Entomological Society of America 99.1 (2006): 96-112.
 – Jones, Almut G. “Observations on reproduction and phenology in some perennial asters.” American Midland Naturalist (1978): 184-197. Accessed 13OCT2022.
 – Park, Mi-Jeong, et al. “Rust disease of Aster pilosus caused by Coleosporium asterum in Korea.” The Plant Pathology Journal 28.3 (2012): 332-332.
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