North America Native Plant

Threetooth Ragwort

Botanical name: Packera tridenticulata

USDA symbol: PATR7

Life cycle: perennial

Habit: subshrub

Native status: Native to Canada ⚘ Native to the lower 48 states  

Synonyms: Senecio densus Greene (SEDE6)  ⚘  Senecio manitobensis Greenm. (SEMA8)  ⚘  Senecio tridenticulatus Rydb. (SETR2)   

Threetooth Ragwort: A Prairie Wildflower Worth Growing If you’re looking to add some authentic prairie charm to your garden, threetooth ragwort (Packera tridenticulata) might just be the wildflower you’ve been searching for. This hardy native perennial brings a splash of golden yellow to late summer landscapes when many other flowers ...

Threetooth Ragwort: A Prairie Wildflower Worth Growing

If you’re looking to add some authentic prairie charm to your garden, threetooth ragwort (Packera tridenticulata) might just be the wildflower you’ve been searching for. This hardy native perennial brings a splash of golden yellow to late summer landscapes when many other flowers are calling it quits for the season.

What is Threetooth Ragwort?

Threetooth ragwort is a native North American wildflower that belongs to the sunflower family. As a perennial herb, it comes back year after year, gradually forming clumps that can reach up to 3 feet tall. Don’t let the name ragwort fool you into thinking it’s weedy – this plant has earned its place in thoughtfully designed native gardens.

You might also encounter this plant under its previous scientific names, including Senecio tridenticulatus, though botanists have since reclassified it as Packera tridenticulata.

Where Does It Naturally Grow?

This prairie native has quite an impressive range, stretching across the Great Plains and into the western United States. You’ll find threetooth ragwort growing wild from the Canadian provinces of Manitoba and Saskatchewan down through states like Colorado, Kansas, Nebraska, North Dakota, South Dakota, Wyoming, and even into parts of New Mexico, Oklahoma, and Texas.

Why Grow Threetooth Ragwort?

There are several compelling reasons to consider adding this native wildflower to your landscape:

  • True native appeal: Supporting local ecosystems by growing plants that naturally belong in your region
  • Late season color: Bright yellow flowers bloom in late summer when your garden needs a pick-me-up
  • Low maintenance: Once established, it’s quite drought tolerant and doesn’t need much fussing
  • Pollinator friendly: The daisy-like yellow flowers attract various beneficial insects
  • Prairie authenticity: Perfect for recreating natural grassland habitats

Garden Design and Landscape Uses

Threetooth ragwort shines in naturalized settings where it can show off its wild prairie heritage. Consider using it in:

  • Prairie restoration projects
  • Wildflower meadows
  • Native plant gardens
  • Xeriscaping projects
  • Background plantings in informal landscapes

With its moderate growth rate and 3-foot mature height, it works well as a mid-border plant or naturalized in larger sweeps where it can form attractive colonies over time.

Growing Conditions and Care

One of the best things about threetooth ragwort is how adaptable it is to different growing conditions. This tough prairie native can handle:

  • Soil types: Clay, loam, or sandy soils – it’s not picky!
  • Sun exposure: Needs full sun to perform its best
  • Water needs: Medium moisture requirements with good drought tolerance once established
  • pH range: Prefers slightly acidic to neutral soil (pH 5.0-7.5)
  • Temperature: Hardy down to -23°F, making it suitable for USDA zones 4-8

The plant prefers areas that receive between 22-45 inches of annual precipitation, making it well-suited to many prairie and plains regions.

Planting and Propagation Tips

Getting threetooth ragwort established in your garden is refreshingly straightforward:

  • From seed: This is the most common method. Seeds can be direct sown in fall or spring
  • Seed density: Plant about 1,700-2,700 seeds per acre for meadow plantings
  • Germination: Seeds don’t require cold treatment, making spring planting simple
  • Spacing: Allow plenty of room as plants can spread moderately over time
  • Root depth: Develops roots at least 12 inches deep, so ensure good soil preparation

Unfortunately, threetooth ragwort isn’t commonly available from commercial nurseries, so you may need to source seeds from native plant specialists or seed companies that focus on prairie species.

Seasonal Interest and Maintenance

This perennial herb offers a lovely seasonal progression in the garden. Its fine-textured green foliage emerges in spring and remains attractive through summer. The real show begins in late summer when clusters of bright yellow, daisy-like flowers appear, providing much-needed color when many other plants are winding down.

Maintenance is minimal – threetooth ragwort doesn’t require regular fertilization and actually prefers moderate fertility levels. The plant has a relatively short lifespan for a perennial, but it can reseed itself in favorable conditions, ensuring its presence in your garden for years to come.

Is Threetooth Ragwort Right for Your Garden?

If you’re passionate about native plants, enjoy low-maintenance gardening, and want to support local wildlife, threetooth ragwort could be an excellent choice. It’s particularly well-suited for gardeners in prairie states who want to create authentic regional landscapes.

However, if you prefer highly manicured gardens or need plants that are readily available at your local garden center, you might want to consider other options. The limited commercial availability can make sourcing this plant a bit of a treasure hunt.

For those committed to growing native species that truly belong in their local ecosystem, threetooth ragwort offers the satisfaction of cultivating a plant that has called North America home for thousands of years. In return, you’ll get cheerful late-season blooms and the knowledge that you’re supporting the web of life that makes prairie ecosystems so special.

How

Threetooth Ragwort

Grows

Growing season

Spring and Summer

Lifespan

Short

Growth form & shape

Multiple Stem and Erect

Growth rate

Moderate

Height at 20 years
Maximum height

3.0

Foliage color

Green

Summer foliage density

Porous

Winter foliage density

Porous

Foliage retention

No

Flowering

Yes

Flower color

Yellow

Fruit/seeds

No

Fruit/seed color

Brown

Allelopath

No

Nitrogen fixing

None

Toxic

None

C:N Ratio

Medium

Fire Resistant

No

Foliage Texture

Fine

Low-growing Grass

No

Resproutability

No

Coppice Ability

No

Bloat

None

Threetooth Ragwort

Growing Conditions

Adapted to Coarse Soil

Yes

Adapted to Medium Soil

Yes

Adapted to Fine Soil

Yes

Anaerobic tolerance

Medium

CaCO₃ tolerance

Low

Cold Stratification

No

Drought tolerance

Medium

Nutrient requirement

Medium

Fire tolerance

High

Frost-free days minimum

100

Hedge tolerance

None

Moisture requirement

Medium

pH range

5.0 to 7.5

Plants per acre

1700 to 2700

Precipitation range (in)

22 to 45

Min root depth (in)

12

Salt tolerance

None

Shade tolerance

Intolerant

Min temperature (F)

-23

Cultivating

Threetooth Ragwort

Flowering season

Late Summer

Commercial availability

No Known Source

Fruit/seed abundance

Medium

Fruit/seed season

Spring to Summer

Fruit/seed persistence

No

Propagated by bare root

Yes

Propagated by bulb

No

Propagated by container

No

Propagated by corm

No

Propagated by cuttings

No

Propagated by seed

Yes

Propagated by sod

No

Propagated by sprigs

No

Propagated by tubers

No

Seed per pound

500000

Seed spread rate

Moderate

Seedling vigor

Medium

Small grain

No

Vegetative spread rate

None

Threetooth Ragwort

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Asterales

Family

Asteraceae Bercht. & J. Presl - Aster family

Genus

Packera Á. Löve & D. Löve - ragwort

Species

Packera tridenticulata (Rydb.) W.A. Weber & Á. Löve - threetooth ragwort

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