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Symphyotrichum divaricatum

southern annual saltmarsh aster

Asteraceae

South-central and southeastern United States

Attracts Pollinators Attracts Butterflies

Native to North America

SunFull Sun – Part Shade

WaterMedium

Overview

Symphyotrichum divaricatum, the southern annual saltmarsh aster, is a slender annual in the Asteraceae growing 8-32 inches (20-80 cm) tall and 6-18 inches (15-45 cm) wide, with wiry, widely branching stems that often sprawl. The narrow, linear to lance-shaped leaves are 1-3 inches (2.5-8 cm) long and reduce in size up the stem. From summer into autumn the branched stems carry many small flower heads, each 0.4-0.6 inch (10-15 mm) across with white to pale lilac rays around a small yellow disc that ages reddish. As an annual, it germinates in spring, flowers and seeds heavily through the season, then dies with frost, persisting only by reseeding. It grows on moist to seasonally wet, often saline or disturbed ground, including marsh edges, ditches, pond margins, floodplains, and roadsides. The wiry, much-branched habit and tiny flowers give it a weedy look, and it self-sows freely where soil stays open and damp.

Native Range

Native to the south-central and southeastern United States, especially Texas and the Gulf Coast, extending through the southern Great Plains and Mississippi valley. It grows on moist to seasonally wet, often saline or alkaline ground such as marsh edges, ditches, pond margins, floodplains, and disturbed roadsides.

Suggested Uses

Used in native plantings, rain gardens, pond and marsh edges, and naturalised wet meadows, sown or self-seeded in open, moist ground and spaced about 10 inches (25 cm) apart. It suits informal, damp, or saline areas where its reseeding is acceptable. The weedy habit and small flowers make it poorly suited to formal beds or dry sites.

How to Identify

Recognised by a much-branched, wiry annual habit with narrow leaves and numerous small heads of white to pale lilac rays around yellow discs. The annual root system and weak, sprawling stems separate it from the perennial saltmarsh asters. The small heads and spreading, divaricate branches give the species its name.

Appearance

Size & Dimensions

Height8" - 2'8"

Width/Spread6" - 1'6"

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Summer Fall

Flowering runs from summer into autumn, mainly July through October, with many small heads opening over a long period. The plant blooms heavily as a single-season annual. Bloom continues until the first hard frost ends it.

Detailed Descriptions

Flower Description

white to pale lilac rays with yellow disc

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 8.0(Neutral)

357912

Soil Types

clay loam silt

Drainagemoist

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Grows in full sun to light shade on moist to seasonally wet soils, including clay, silt, and saline or alkaline ground, at a pH around 6.0-8.0. As a warm-season annual it germinates in spring, needs steady moisture through the growing season, and tolerates brief flooding and salt. It needs no fertiliser on most sites and self-sows readily where soil stays bare and damp. Seedlings can be thinned to limit crowding. The plant completes its life cycle in one season and does not overwinter.

Pruning

Requires no pruning as a short-lived annual. Sprawling stems can be trimmed to keep plants within bounds, and spent plants are pulled once seed has set. Clearing plants before seed drop limits self-sowing the following year.