Perennials

Aconitum bicolor

Bicolor Monkshood

Ranunculaceae

Europe, western Asia (hybrid origin)

At a Glance

TypePerennial
HabitUpright
FoliageDeciduous
Height3–5 feet (90–150 cm)
Width18–24 inches (45–60 cm)
Maturity3 years

Growing Zones

USDA Hardiness Zones

3 - 7
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Attracts Pollinators
Deer Resistant
Maintenancemoderate

Overview

Aconitum bicolor is an upright herbaceous perennial reaching 3–5 feet (90–150 cm) tall with a spread of 18–24 inches (45–60 cm), forming an erect clump of deeply divided foliage topped by racemes of hooded flowers in late summer. Leaves are palmately divided, 3–6 inches (7.5–15 cm) wide, with five to seven deeply cut lobes and sharply serrated margins, dark green and glossy above. Flowers are distinctively bicolor — white with blue-violet to purple margins and a prominent hood (galea) — arranged in elongated racemes 12–18 inches (30–45 cm) long from July through September. The hooded flower form is characteristic of the genus Aconitum and distinguishes it from most other late-summer perennials. Stems are erect and self-supporting in most conditions but may require staking at the tall end of the height range. Aconitum bicolor is considered a hybrid or intermediate form between A. napellus and A. variegatum. All parts of the plant contain aconitine alkaloids and are highly toxic to humans, pets, and livestock.

Native Range

Aconitum bicolor is of garden or hybrid origin, combining traits of A. napellus and A. variegatum, both native to mountainous regions of Europe and western Asia. Parent species occur in moist mountain meadows, stream margins, and alpine woodland edges at elevations of 2,000–8,000 feet (600–2,400 m).

Suggested Uses

Planted in partially shaded borders, woodland garden edges, and stream-side plantings at 18–24 inch (45–60 cm) spacing. The bicolor white-and-blue-violet late-summer flowers on tall erect stems extend the bloom season in shade gardens beyond midsummer. Suited to zones 3–7 in cool, consistently moist sites. Not suited to hot-summer climates above zone 7, dry soils, or gardens frequented by unsupervised children or grazing animals due to high toxicity.

How to Identify

Aconitum bicolor is identified by the bicolor flowers — white with blue-violet to purple margins and a strongly arched hood (galea) — produced on elongated racemes in July–September. The deeply palmate dark green foliage, 3–6 inches (7.5–15 cm) wide, with five to seven sharply lobed and serrated segments is characteristic of the Aconitum genus. Distinguished from solid-colored Aconitum species by the white-and-blue bicolor flower. Distinguished from Delphinium by the closed hood rather than open spur structure. The combination of hooded bicolor flowers and deeply divided dark green foliage is diagnostic.

Appearance

Size & Dimensions

Height3' - 5'
Width/Spread1'6" - 2'

Reaches mature size in approximately 3 years

Colors

Flower Colors

white
blue
purple

Foliage Colors

dark green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~8 weeks
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SummerFall
Bicolor white-and-blue-violet hooded flowers appear on elongated racemes 12–18 inches (30–45 cm) long from July through September, lasting 6–8 weeks. Individual flowers are 1–1.5 inches (2.5–4 cm) long. Racemes open progressively from base to tip.

Detailed Descriptions

Flower Description

white with blue-violet to purple margins and hood

Foliage Description

dark glossy green

Growing Conditions

Sun Requirements

Partial Shade
Full Shade
Requires 2-6 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

High

Frost Tolerance

hardy

Time to Maturity

2–3 years

Care & Maintenance

Care Guide

Plant in moist, well-drained, humus-rich soil with a pH of 5.5–7.0 in partial shade to full sun where summers are cool. Afternoon shade is beneficial where summer temperatures exceed 75°F (24°C). Water consistently — Aconitum does not tolerate dry soil; water weekly during dry periods throughout the growing season. Mulch to retain soil moisture and keep roots cool. Performs in zones 3–7; heat tolerance declines sharply above zone 7. Established clumps should be divided every 3–4 years in spring to maintain vigor. All plant parts are highly toxic — wear gloves when handling and keep away from children and pets.

Pruning

Cut spent flower racemes back to the basal foliage after bloom to tidy the plant; a second flush of smaller racemes sometimes follows. Cut stems to the ground in late fall after frost. Division in early spring, before significant foliage emergence, is the standard method for propagation and clump renewal. Wear gloves — all parts contain toxic alkaloids.

Pruning Schedule

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fallearly spring

Maintenance Level

moderate

⚠️ Toxicity Warning

Toxic to pets and humans
Aconitum bicolor (Bicolor Monkshood) - Identification & Care Guide | PlantRef