perennial

Smallflower Hairy Willowherb

The Story

Plant Bio

Epilobium parviflorum, commonly known as smallflower hairy willowherb, is an erect herbaceous perennial native to Eurasia that establishes in damp, open habitats. The stiffly branched stems are densely covered in soft, spreading hairs and carry narrow, lance-shaped leaves that transition from opposite to alternate arrangement near the top.

This species is distinguished by its tiny, pale pink to pale purple four-petaled flowers, which measure only six to eight millimeters across and open individually in the upper leaf axils. Following bloom, it produces slender seed capsules that split to release hundreds of wind-borne, plumed seeds.

Uses & Benefits:

Provides a wild, naturalistic appearance along pond margins and wet garden spots with its soft, hairy foliage and tiny pink flowers.

Thrives in heavy, wet clay soils where other garden perennials struggle to survive.

Attracts native bees, hoverflies, and honey bees to damp garden areas during the midsummer blooming period.

Essentials

At a Glance

Plant Type

Perennial

Height

31"

Width

24"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7, 8, 9

Water

High

Humidity

High

Lifespan

Perennial

Native To

Eurasia

Toxicity

Non-toxic

Bloom period

Summer

In flower about 3 months of the year

Planting

How to Grow

Select a site in full sun to partial shade with consistently moist, poorly drained, or wet soil.
Plant potted liners in spring, spacing them twelve to eighteen inches apart to allow for stoloniferous spread.
Water regularly to maintain constant soil moisture, as the root system will not tolerate drying out.
Cut back the entire plant to the ground in late winter to clear dead stems and encourage fresh spring growth.

Pro Tip

Cut back spent flower stalks immediately after the summer bloom to prevent the wind-dispersed seeds from colonizing surrounding garden beds.

Keep It Thriving

Care Guide

Do

Keep the soil consistently moist or wet, especially during hot summer spells.
Deadhead spent flowers promptly to control aggressive localized self-seeding.
Divide established root clumps in early spring to manage the plant's spread.

Don't

Do not allow the soil to dry out completely, which causes rapid foliage decline.
Avoid applying heavy fertilizers, which leads to weak, floppy, and overly leggy stems.
Do not plant near pristine wetland areas where wind-blown seeds could escape and naturalize.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Deadhead
Divide
Pest Check
Prune

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Bog GardensRain GardensPond EdgesWildflower Meadows

Companion Plants

Verbena hastata Chelone glabra Carex stricta

Multiply

Propagation Methods

Good to Know

Common Questions

Smallflower Hairy Willowherb questions

What zones can Smallflower Hairy Willowherb grow in?

Smallflower Hairy Willowherb is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

When does Smallflower Hairy Willowherb bloom?

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

Does Smallflower Hairy Willowherb need full sun?

Smallflower Hairy Willowherb does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.