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Eupatorium serotinum

late boneset

Asteraceae Eastern and central North America

Attracts Pollinators Attracts Butterflies Deer Resistant

Native to North America

SunFull Sun – Part Shade

WaterMedium

HardinessZones 4–8

Overview

Eupatorium serotinum is a clump-forming perennial in the aster family, growing 3 to 6 feet (0.9-1.8 m) tall on stout, branched, finely hairy stems. The opposite leaves are lance-shaped, 3-8 inches (8-20 cm) long, sharply toothed, long-stalked, and prominently three-veined. From late summer into autumn the branched stem tips carry broad, flat-topped clusters of many small dull-white flower heads, each made of about 9 to 15 tubular disc florets without rays. The clusters draw large numbers of bees, wasps, butterflies, and other late-season insects. The plant spreads by short rhizomes and abundant wind-borne seed, forming colonies in moist, open ground, floodplains, and disturbed sites. It self-sows freely and can spread beyond where it is wanted in fertile soil. The foliage contains compounds that make it bitter and unpalatable to deer and livestock.

Native Range

Native to the eastern and central United States and parts of northeastern Mexico, from New York and Iowa south to Florida and Texas. It grows in moist meadows, floodplains, ditches, woodland edges, and disturbed open ground.

Suggested Uses

Used in rain gardens, moist meadows, pond margins, and the back of large borders for late-season bloom and pollinator support, spaced 24-36 inches (60-90 cm) apart. Its autumn flowers feed bees, wasps, and migrating butterflies when little else blooms. Because of its size and spread, it suits naturalistic plantings more than small formal beds.

How to Identify

Recognized by tall, branched stems with opposite, sharply toothed, three-veined, long-stalked leaves and broad, flat-topped clusters of small dull-white rayless flower heads in autumn. The numerous heads, each with only 9 to 15 florets, separate it from the white snakeroots and other bonesets. The leaves are stalked, unlike the stalkless, joined leaves of common boneset E. perfoliatum.

Appearance

Size & Dimensions

Height3' - 6'

Width/Spread2' - 3'

Colors

Flower Colors

white

Foliage Colors

green

Bloom Information

Bloom Period

~10 weeks

Summer Fall

Dull-white flower clusters open from August through October, among the last perennials to bloom before frost. The display lasts several weeks and draws heavy insect traffic. Fluffy wind-borne seed follows from autumn into early winter.

Detailed Descriptions

Foliage Description

Green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 5-12 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 Range5.5 - 7.5(Neutral)

357912

Soil Types

clay loam silt

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years to full size

Care & Maintenance

Care Guide

Grows in full sun to part shade on moist to wet, average to fertile soil and tolerates clay, occasional flooding, and a wide pH range. It withstands short dry spells once established but grows tallest and fullest with steady moisture. Plants are hardy to about -30F (-34C) in zones 4-8 and die back to the ground each winter. The rhizomes and self-sown seed build colonies, so plants may need thinning to stay in bounds. Stems can lean in shade or rich soil and may need support or cutting back. No feeding is needed on average ground.

Pruning

Cutting stems back by half in early summer reduces height and lessens flopping. Spent flower heads can be removed before seed sheds to limit self-sowing, or left standing for winter structure. Stems can be cut to the ground in late autumn or early spring.