What hardiness zones is Ageratina altissima 'Chocolate' suitable for?

Ageratina altissima 'Chocolate' is suitable for USDA hardiness zones 4, 5, 6, 7, 8.

What are the sun requirements for Ageratina altissima 'Chocolate'?

Ageratina altissima 'Chocolate' requires Part Shade.

How much water does Ageratina altissima 'Chocolate' need?

Ageratina altissima 'Chocolate' has Medium water needs.

Perennials

Ageratina altissima 'Chocolate'

Chocolate White Snakeroot

AsteraceaeEastern North America

At a Glance

TypePerennial

HabitUpright

FoliageDeciduous

Height36-48 inches (90-120 cm)

Width24-36 inches (60-90 cm)

Maturity2 years

Growing Zones

USDA Hardiness Zones

4 - 8

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Attracts Butterflies

Deer Resistant

Native to North America

Maintenancemoderate

Overview

Ageratina altissima 'Chocolate' is an upright, clump-forming perennial reaching 36–48 inches (90–120 cm) tall and 24–36 inches (60–90 cm) wide. This cultivar of A. altissima produces dark chocolate-purple to bronze-green foliage, darker than the species type which has medium green leaves. Leaves are opposite, ovate, 3–5 inches (8–13 cm) long with coarsely toothed margins. New spring foliage emerges intensely dark purple, fading to bronze-green as summer temperatures rise above 80°F (27°C). Flat-topped clusters of small white flowers 3–5 inches (8–13 cm) across appear August through October, contrasting with the dark foliage. Individual flower clusters last 2–3 weeks; total bloom period extends 4–6 weeks. Plants spread by rhizomes and self-seed freely, producing 30–50 seedlings per plant annually if not deadheaded. Seedlings do not all retain the dark foliage color; approximately 50% revert to green. Stems are upright but may lean or flop in full shade or overly rich soils. All parts contain tremetol, which is toxic to livestock and humans if ingested in quantity. Historically, this toxin caused 'milk sickness' in humans who consumed milk from cattle that had grazed on the plant.

Native Range

The species A. altissima is native to eastern North America, from southern Canada through the eastern United States west to Texas. Found in moist woodland edges, stream banks, and partially shaded roadsides at 200–5,000 feet (60–1,500 m) elevation. The cultivar 'Chocolate' was selected from wild populations.

Suggested Uses

Commonly planted in woodland gardens, shade borders, and naturalized areas at 24–30 inch (60–75 cm) spacing. Late bloom season complements earlier-flowering shade perennials. Prolific self-seeding and rhizome spread make this cultivar unsuitable for small, formal plantings without regular maintenance to control spread.

How to Identify

Distinguished from the green-leaved species type by dark chocolate-purple to bronze-green foliage. Leaves opposite, ovate, 3–5 inches (8–13 cm) long with coarsely toothed margins. Flat-topped white flower clusters 3–5 inches (8–13 cm) across appear in late summer. Distinguished from Eupatorium species (now reclassified) by opposite rather than whorled leaf arrangement and smaller overall flower cluster size.

Appearance

Size & Dimensions

Height3' - 4'

Width/Spread2' - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

white

Foliage Colors

purple

green

Fall Foliage Colors

purple

Bloom Information

Bloom Period

~6 weeks

SummerFall

Flowers August through October in zones 4–8. Individual flower clusters last 2–3 weeks; total bloom period extends 4–6 weeks. In zone 8, bloom may begin in late July. Bloom timing is late in the perennial season, filling a gap when many summer perennials have finished.

Detailed Descriptions

Flower Description

White

Foliage Description

Dark chocolate-purple to bronze-green, opposite, toothed

Growing Conditions

Sun Requirements

Partial Shade

Full Sun

Requires 3-8 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 - 7.0(Neutral)

357912

Soil Types

loamclay

Drainage

moist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Water regularly during the first growing season to establish. Established plants require consistent moisture; leaf margins scorch during prolonged drought. Foliage color is darkest in partial shade with 3–6 hours of direct sun. Full sun intensifies purple color in spring but may cause leaf scorch in hot climates (zones 7–8). Self-seeding is prolific; remove spent flower heads before seeds disperse to prevent volunteer seedlings. Pinch stems by one-third in early June to reduce mature height and promote bushier growth. Rhizome spread is moderate at 4–6 inches (10–15 cm) annually.

Pruning

Cut all stems to ground level in late fall after frost or in early spring (March–April) before new growth emerges. Pinch growing tips by one-third in early June to reduce height by 6–12 inches (15–30 cm) and prevent late-season flopping. Deadhead spent flower clusters promptly to limit self-seeding. Divide clumps every 3–4 years in spring to manage spread.

Pruning Schedule

early springsummer

Maintenance Level

moderate

⚠️ Toxicity Warning

Toxic to pets and humans