North America Native Plant

Hairy Smartweed

Botanical name: Polygonum hirsutum

USDA symbol: POHI3

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Persicaria hirsuta (Walter) Small (PEHI6)   

Hairy Smartweed: A Native Wetland Wonder for Specialized Gardens If you’re looking to add authentic native character to a wet spot in your landscape, hairy smartweed (Polygonum hirsutum) might just be the unsung hero your garden needs. This southeastern native brings subtle charm and important ecological benefits to wetland gardens, ...

Rare plant alert!

Region: Conservation status by state

Status: S3S4: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Hairy Smartweed: A Native Wetland Wonder for Specialized Gardens

If you’re looking to add authentic native character to a wet spot in your landscape, hairy smartweed (Polygonum hirsutum) might just be the unsung hero your garden needs. This southeastern native brings subtle charm and important ecological benefits to wetland gardens, though it’s definitely not your typical backyard flower.

Meet the Hairy Smartweed

Don’t let the common name fool you – while hairy smartweed may sound a bit rough around the edges, this perennial forb is actually a delicate beauty. Also known by its scientific synonym Persicaria hirsuta, this herbaceous plant produces clusters of small white to pinkish flowers that dance above narrow, softly textured leaves. As a member of the smartweed family, it shares the characteristic spike-like flower clusters that make these plants instantly recognizable to native plant enthusiasts.

Where Hairy Smartweed Calls Home

This southeastern specialty is native to six states across the lower Southeast: Alabama, Florida, Georgia, Mississippi, North Carolina, and South Carolina. As a true child of the coastal plain and piedmont regions, hairy smartweed has evolved to thrive in the unique conditions found in these areas.

A Plant with Specific Needs

Here’s where things get interesting – and a bit challenging for the average gardener. Hairy smartweed is what botanists call an obligate wetland species, which is a fancy way of saying it absolutely, positively needs wet feet to survive. We’re talking consistently moist to soggy soil conditions, not just the occasional deep watering.

This perennial thrives in USDA hardiness zones 7-10, enjoying full sun to partial shade as long as the moisture requirements are met. Think of it as nature’s way of creating a plant perfectly designed for bog gardens, rain gardens, and wetland restoration projects.

Why Consider Growing Hairy Smartweed?

While this isn’t a plant for every garden, it has some compelling benefits for the right situation:

  • True native credentials: Supporting authentic regional flora
  • Pollinator magnet: The small flowers attract bees and other beneficial insects
  • Low maintenance: Once established in proper conditions, it pretty much takes care of itself
  • Wetland restoration: Perfect for rain gardens and naturalistic wet areas
  • Unique garden feature: Adds authentic wetland character to specialized landscapes

A Word of Caution: Rarity Matters

Before you rush out to find hairy smartweed, there’s something important to know. This species carries a Global Conservation Status of S3S4, indicating it may face some population pressures in parts of its range. If you’re interested in growing this plant, make sure to source it responsibly from reputable native plant nurseries that propagate their stock rather than wild-collecting.

Growing Hairy Smartweed Successfully

Success with hairy smartweed comes down to one key factor: water, water, water. Here’s how to give this wetland native what it craves:

  • Location: Choose the wettest spot in your garden – areas that stay soggy after rain are ideal
  • Soil: Any soil type works as long as it stays consistently moist to wet
  • Light: Full sun to partial shade (6+ hours of sun preferred)
  • Planting: Spring planting works best, giving roots time to establish before winter
  • Maintenance: Minimal once established – just ensure consistent moisture

Is Hairy Smartweed Right for Your Garden?

Let’s be honest – this isn’t a plant for everyone. Hairy smartweed requires specific conditions that many typical garden settings can’t provide. However, if you have a naturally wet area, are creating a rain garden, or are involved in wetland restoration, this native gem could be exactly what you need.

Consider hairy smartweed if you have:

  • A naturally wet or boggy area in your landscape
  • Plans for a rain garden or bioswale
  • Interest in native wetland restoration
  • A desire to support specialized native pollinators

For most gardeners dealing with typical well-drained garden beds, you might want to explore other native smartweed species or wetland plants that can handle less soggy conditions.

The Bottom Line

Hairy smartweed represents the fascinating world of specialized native plants – those species that have carved out specific ecological niches and thrive in conditions that would challenge most garden plants. While it won’t work in every landscape, for the right situation and the right gardener, it offers a chance to grow something truly unique and regionally authentic.

If you’re ready to embrace wetland gardening and have the consistently moist conditions this plant demands, hairy smartweed could add a distinctive native touch to your specialized garden. Just remember to source it responsibly and be prepared to keep those roots happily waterlogged!

Hairy Smartweed

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Caryophyllidae

Order

Polygonales

Family

Polygonaceae Juss. - Buckwheat family

Genus

Polygonum L. - knotweed

Species

Polygonum hirsutum Walter - hairy smartweed

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA