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Swamp-loosestrife

Decodon verticillatus

Last reviewed: August 2026

Swamp-loosestrife (Decodon verticillatus)
Photo: Robert H. Mohlenbrock. USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln. Courtesy of USDA NRCS Wetland Science Institute. / Wikimedia Commons (Public domain)

Toxicity unknown

Swamp-loosestrife (Decodon verticillatus) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

The USDA PLANTS Database (opens in new tab) does not flag Swamp-loosestrife as toxic to livestock.

Light

part sun

Water

high

Size

36"–120" H × 24"–60" W

Bloom

Jul, Aug, Sep

Native to

AL, AR, CT, DE and 29 more states

Pollinators

bees, butterflies

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Browse plants for this ecoregion

South Central PlainsOzark HighlandsNorthern Lakes and ForestsNorth Central Hardwood ForestsDriftless AreaSoutheastern Wisconsin Till PlainsEastern Corn Belt PlainsSouthern Michigan/Northern Indiana Drift PlainsHuron/Erie Lake PlainsNortheastern HighlandsNortheastern Coastal ZoneNorthern Allegheny PlateauErie Drift PlainNorthern ForestsMiddle Atlantic Coastal PlainNorthern PiedmontSoutheastern PlainsRidge and ValleyInterior PlateauInterior River Valleys and HillsMississippi Alluvial PlainSouthern Coastal PlainAcadian Plains and HillsEastern Great Lakes LowlandsAtlantic Coastal Pine Barrens

Swamp-loosestrife is a native wetland shrub that produces clusters of bright magenta flowers from July through September. It thrives in consistently moist to wet soils and can form dense colonies over time through its sprawling, vine-like growth habit.

In an HOA neighborhood

Swamp-loosestrife takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.

Works well in: backyard only.

  • Requires consistently wet conditions
  • Sprawling vine-like growth looks uncontrolled
  • Can spread aggressively to form colonies

Wildlife value

The showy magenta flowers attract native bees and butterflies throughout the late summer blooming period. Dense growth provides good cover for wildlife in wetland areas.

Common questions

How much sun does Swamp-loosestrife need?
Swamp-loosestrife grows best in part sun conditions.
When does Swamp-loosestrife bloom?
Swamp-loosestrife blooms in July, August, and September.
Where is Swamp-loosestrife native?
Swamp-loosestrife (Decodon verticillatus) is native to AL, AR, CT, DE and 29 more states, per vouchered herbarium specimen records and regional native plant society lists.
Is Swamp-loosestrife toxic to livestock?
The USDA PLANTS Database does not flag Swamp-loosestrife as toxic to livestock.
What pollinators does Swamp-loosestrife attract?
Swamp-loosestrife draws bees and butterflies.
Is Swamp-loosestrife HOA-friendly?
Swamp-loosestrife takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

Ready to grow Swamp-loosestrife? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.

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