perennial

Woolly Burdock

Arctium tomentosum

The Story

Plant Bio

Arctium tomentosum, the woolly burdock, is a robust biennial herb that forms a coarse basal rosette of massive, heart-shaped leaves in its first year before sending up a tall, branched flowering stem in its second. The species is distinguished by a dense, felt-like white webbing that covers both the undersides of the foliage and the globose flower heads.

This species is separated from other common burdocks by the heavy, cobweb-like hairs on its flower involucres and its flat-topped, corymb-like flower clusters. The purplish-red flower heads feature hooked bracts that cling tightly to passing animals and clothing to disperse the seeds.

Uses & Benefits:

The massive, felted basal leaves and unique woolly flower heads provide a bold, architectural texture in wild gardens.

The deep taproot helps break up compacted soils, and the roots and seeds are harvested for traditional herbal preparations.

The nectar-rich purple flowers attract native bees, butterflies, and other beneficial pollinating insects.

Essentials

At a Glance

Plant Type

Perennial

Height

79"

Width

59"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7

Water

Moderate

Humidity

Moderate

Lifespan

Biennial

Native To

Eurasia

Toxicity

Skin Irritant / Toxic if Ingested

Bloom period

Summer – Fall

In flower about 6 months of the year

Planting

How to Grow

Sow seeds directly into prepared garden beds in spring or fall, pressing them lightly into the soil surface as they require light to germinate.
Select a site in full sun to partial shade with deep, well-draining soil to accommodate the long, fleshy taproot.
Water young seedlings regularly to keep the soil moist until they establish a robust root system.
Provide minimal supplemental fertilizer, as the plant thrives naturally in nutrient-rich, disturbed, or calcareous soils.

Pro Tip

Cut the flowering stalks down to the ground immediately after the blooms fade to prevent the plant from self-seeding aggressively and becoming a weed.

Keep It Thriving

Care Guide

Do

Wear gloves when handling mature plants to avoid contact dermatitis from the foliage.
Remove spent flower heads before they mature into dry, clinging burs.
Grow in a dedicated, contained area of the garden to manage its self-seeding tendency.

Don't

Do not plant near pathways or livestock pastures where the hooked seed burs can cling to clothing or animal fur.
Do not overwater or plant in poorly drained soils where the deep taproot is susceptible to rot.
Do not prune into the main stem during the active growing season if you wish to see the second-year flowers.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Pest Check
Plant
Prune
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Naturalized AreasMedicinal GardensWildflower Gardens

Companion Plants

Echinacea purpurea Liatris spicata Verbascum thapsus

Multiply

Propagation Methods

Good to Know

Common Questions

Woolly Burdock questions

What zones can Woolly Burdock grow in?

Woolly Burdock is hardy in USDA Zones 4–7. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

When does Woolly Burdock bloom?

Woolly Burdock typically blooms in summer through fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Woolly Burdock need full sun?

Woolly Burdock does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Woolly Burdock drought tolerant?

Yes — once established (usually after the first full season), Woolly Burdock handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.