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Swamp Aster

Name: Swamp Aster
Brand: Akène
SKU: AKE-SEMENCES
Price: 4.99 CAD
Availability: OutOfStock

Common name Purple-Stemmed Aster

Latin name Symphyotrichum puniceum

Quantity per packet Minimum 200 seeds

This native perennial strongly supports biodiversity by providing an important late-season source of nectar. It also contributes to the ecological restoration of wetlands and native prairie habitats.

Product information

Product
identification

Common namePurple-Stemmed Aster

Latin nameSymphyotrichum puniceum

FamilyAsteraceae

TypeNative perennial

CyclePerennial

Quantity per packMinimum 200 seeds

Product
description

Scarlet Aster (Symphyotrichum puniceum) is a majestic native perennial that brings vibrant color and life to the garden when many other plants are finishing their season. From late summer until the first frosts, it is covered with abundant rose-purple to deep violet blooms that brighten naturalistic landscapes and pollinator gardens. Its upright habit, reaching 90 to 150 cm (3 to 5 ft) in height, adds striking vertical structure to perennial borders while creating a spectacular display in prairie-style plantings. Extremely hardy and perfectly adapted to Canadian climates, this native perennial returns reliably year after year and is one of the finest choices for biodiversity-friendly gardens.

Scarlet Aster thrives in full sun to partial shade in fertile, moist to wet, well-drained loamy to clay soils. Seeds can be sown in autumn or in spring after a period of cold stratification, approximately 3 mm deep. Consistent moisture encourages uniform germination and strong seedling establishment. Once established, this native perennial requires very little maintenance beyond a light application of compost in spring and occasional watering during prolonged dry periods. Leave the dry stems standing through winter to provide shelter for beneficial insects, then cut them back the following spring.

Ideal for pollinator gardens, rain gardens, riparian plantings, and ecological restoration projects, Scarlet Aster pairs beautifully with Joe-Pye Weed, Goldenrods, Cardinal Flower, and Northern Blue Flag Iris. Its late-season blooms provide an essential source of nectar and pollen for native bees, bumblebees, butterflies, and many other beneficial insects at a critical time of year when floral resources become scarce. Seeds left on the plants through autumn may also provide food for wildlife. Combining outstanding ornamental beauty with exceptional ecological value, Symphyotrichum puniceum enriches native ecosystems while extending the beauty of the garden well into autumn.

Sowing
guide

Sowing periodAutumn or spring after cold stratification

Best time

Autumn or spring after cold stratification

Sowing depth3 mm

Spacing / density

45 to 60 cm (18 to 24 in)

Germination temperature18 to 22°C (64 to 72°F)

Germination time15 to 30 days

Propagation

Propagate by seed or by dividing established clumps.

Growing
method

Purple-Stemmed Aster is easily grown from cold-stratified seeds. Sow the seeds about 3 mm deep in a rich, moist growing medium and maintain temperatures between 18 and 22°C (64 to 72°F). Germination usually occurs within 15 to 30 days when consistent moisture is maintained. This native perennial prefers moist soils in full sun to partial shade. Once established, it returns reliably every year and develops into a large, vigorous perennial. Its late-season flowers provide an essential nectar source for pollinators throughout Canada.

Soil
and care

ExposureFull sun to partial shade

Soil

Rich, moist loamy to clay soil. This species thrives in fertile soils that retain moisture while remaining well drained.

Soil pH5.5 to 7.0

Watering

Water regularly to keep the soil consistently moist. This species prefers sites that do not dry out completely during summer.

Fertilization

A light application of compost or balanced organic fertilizer each spring is generally sufficient. Naturally fertile soils encourage vigorous growth and abundant flowering.

Care levelModerate

In spring, remove the previous year's dry stems and apply a thin layer of compost around the plants. Throughout summer, keep the soil evenly moist to support vigorous growth. During drought, supplemental watering encourages more abundant flowering. Leave the seed heads standing through autumn to feed birds and support wildlife. Cut the stems back the following spring to protect overwintering beneficial insects.

Container
growing

Recommended pot size

30 to 40 cm (12 to 16 in)

Purple-Stemmed Aster can be grown in a large, deep container with excellent drainage. Use a rich growing medium that retains moisture without becoming waterlogged. This native perennial benefits from regular watering during warm weather to support vigorous growth and abundant late-season blooms. In containers, it attracts numerous pollinators to patios and balconies while creating a spectacular natural display.

Bloom,
harvest
and garden

Its spectacular late-season blooms provide an essential food source for pollinators at a critical time of year while adding impressive height, color, and biodiversity to natural landscapes.

This native perennial strongly supports biodiversity by providing an important late-season source of nectar. It also contributes to the ecological restoration of wetlands and native prairie habitats.

Garden use

Purple-Stemmed Aster is ideal for pollinator gardens, riparian plantings, rain gardens, and ecological restoration projects. It pairs beautifully with Goldenrods, Spotted Joe-Pye Weed, and native grasses to create naturalistic plantings rich in biodiversity. Its late-season flowering extends the beauty of the garden well into autumn while providing critical resources for pollinators.

Bloom period

Late-season blooms cover the plant with rose-purple flowers that attract a remarkable diversity of pollinators and brighten the garden until the first frosts.

Flower colorRose-purple to deep violet

Foliage colorGreen

Harvest

September to October

Fruiting

Achenes containing numerous seeds

Wildlife appealBees and butterflies

Size
and facts

Height90 to 150 cm (36 to 60 in.)

Spread30 to 60 cm (12 to 24 in)

Growth rateModerate

Hardiness zoneUSDA Zones 3–8

Minimum temperature-40°C (-40°F)

Foliage typeDeciduous

Papillonstrue

Insectes utilestrue

Planting
partners

Good companions

Spotted Joe-Pye Weed, Goldenrod, Cardinal Flower, Northern Blue Flag Iris

Avoid planting with

Lavender, Cotton Lavender, Sedum, Blanket Flower

Recipe
and inspiration

Young tender leaves may be used sparingly as a wild green when correctly identified, but Purple-Stemmed Aster is grown primarily for its ornamental and ecological value. The flowers may be used in natural floral arrangements, while the plant's greatest contribution comes from its late-season blooms that provide essential nectar and pollen for pollinators when few native species remain in flower.

Frequently asked questions

When should I sow Purple-Stemmed Aster seeds? +

Purple-Stemmed Aster seeds are best sown in autumn or in spring after a period of cold stratification to improve germination.

Why is Purple-Stemmed Aster so attractive to pollinators? +

Its abundant late-season blooms provide nectar and pollen when many other flowers have completed their flowering cycle, making it especially valuable to pollinators.

Can Purple-Stemmed Aster be grown in a rain garden? +

Yes. This species thrives in rich, moist soils and is an excellent choice for rain gardens and other moisture-retentive landscapes.

Is Purple-Stemmed Aster hardy in Canada? +

Yes. Purple-Stemmed Aster is fully hardy and perfectly adapted to the severe winters found throughout much of Canada.

How do you care for Purple-Stemmed Aster? +

Consistently moist soil, an annual application of compost, and cutting back old stems in spring are generally all that is required to keep this native perennial healthy.

The availability of our seeds varies depending on seasonal availability, production schedules and supplier inventory. Certain varieties may only be offered for a limited time based on their natural growth cycle, sowing period or available stock. These product pages are designed to help and inspire gardeners in choosing the right seeds for vegetable gardens, flower beds, pollinator gardens, container growing, naturalization projects and sustainable outdoor spaces.