Wildflower (forb) · Fabaceae
Purple milkvetch
Astragalus agrestis
Purple milkvetch is recorded as native to 15 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 258 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
Purple milkvetch at a glance
- Native in
- 258 counties, across 15 states and territories
- Estimated cold hardiness
- Zone 4a PLANTS minimum temperature −33°F
- Mature height
- 1 ft PLANTS mature height
- Light and water
- Full sun (shade-intolerant) Low water use
Estimated cold hardiness: zone 4a. PLANTS gives a minimum temperature of −33°F; zone 4a winters bottom out at −30°F, the coldest half-zone that stays within that limit.
Purple milkvetch is recorded as native to 15 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 258 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 258 where it is listed.
Native counties by state
- California 2 counties
- Colorado 22 counties
- Idaho 17 counties
- Iowa 2 counties
- Minnesota 51 counties
- Montana 38 counties
- Nebraska 3 counties
- Nevada 6 counties
- New Mexico 7 counties
- North Dakota 40 counties
- Oregon 8 counties
- South Dakota 15 counties
- Utah 21 counties
- Washington 9 counties
- Wyoming 17 counties
Growing traits
Values from the PLANTS characteristics record. “Not recorded” means PLANTS has no value; nothing here is estimated except the zone.
Growth
- Growth habit
- Forb/herb
- Duration
- Perennial
- Mature height
- 1 ft
- Growth rate
- Moderate
- Growth form
- Rhizomatous
- Shape
- Decumbent
- Lifespan
- Short
- Active growth period
- Spring and Summer
Light and water
- Shade tolerance
- Intolerant (full sun (shade-intolerant))
- Moisture use
- Low water use
- Drought tolerance
- Low
- Tolerance of waterlogged soil
- Medium
- Precipitation range
- 8 to 40 in per year
Soil
- Soil textures
- Medium
- pH range
- 6.3 to 7.7
- Lime (CaCO₃) tolerance
- Low
- Salinity tolerance
- None
- Fertility requirement
- Medium
- Minimum root depth
- 10 in
Climate
- Minimum temperature
- −33°F
- Estimated cold hardiness
- Zone 4a and warmer
- Minimum frost-free days
- 175
- Fire tolerance
- High
Flowers, leaves and fruit
- Flower color
- Purple
- Showy flowers
- Yes
- Bloom period
- Summer
- Foliage color
- Green
- Showy in fall
- No
- Keeps leaves
- No
- Fruit color
- Brown
Other
- Toxicity
- Slight
- Nitrogen fixation
- Medium
- Nursery availability
- No Known Source
- Family
- Fabaceae
- PLANTS symbol
- ASAG2
Source & data date
- Source
- USDA NRCS PLANTS Database: county distribution records, native status and plant characteristics. CC0 (public domain dedication, per the data.gov catalog record).
- Kew’s World Checklist of Vascular Plants (WCVP): native or introduced status by state. CC BY 3.0.
- USGS US-RIIS (ver. 2.0): species listed as introduced are excluded. CC0.
- Citation
- USDA, NRCS. 2026. The PLANTS Database (https://plants.usda.gov, 11/04/2026). National Plant Data Team, Greensboro, NC USA.
- Govaerts R. (ed.) (2026). WCVP: World Checklist of Vascular Plants. Facilitated by the Royal Botanic Gardens, Kew. Data file dated 2026-06-04, http://sftp.kew.org/pub/data-repositories/WCVP/ (retrieved 2026-11-04). Paper: Govaerts R. et al. (2021) The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. Scientific Data 8, 215.
- Data date
- Retrieved from PLANTS on November 4, 2026; WCVP data file dated June 4, 2026.
- Scope
- Astragalus agrestis (PLANTS symbol ASAG2).
- Method
- A species is listed when it is recorded as native to the state in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in the county by USDA PLANTS. Species PLANTS labels both native and introduced are listed separately. Full method · All sources