Wildflower (forb) · Polemoniaceae
Smooth phlox
Phlox glaberrima
Smooth phlox is recorded as native to 16 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 371 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
Smooth phlox at a glance
- Native in
- 371 counties, across 16 states and territories
- Estimated cold hardiness
- Zone 4b PLANTS minimum temperature −28°F
- Mature height
- 3 ft PLANTS mature height
- Light and water
- Sun to part shade High water use
Estimated cold hardiness: zone 4b. PLANTS gives a minimum temperature of −28°F; zone 4b winters bottom out at −25°F, the coldest half-zone that stays within that limit.
Smooth phlox is recorded as native to 16 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 371 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 371 where it is listed.
Native counties by state
- Alabama 20 counties
- Arkansas 25 counties
- Florida 7 counties
- Georgia 10 counties
- Illinois 74 counties
- Indiana 37 counties
- Kentucky 41 counties
- Louisiana 5 counties
- Maryland 1 county
- Mississippi 24 counties
- Missouri 17 counties
- North Carolina 34 counties
- Ohio 7 counties
- Tennessee 45 counties
- Virginia 21 counties
- Wisconsin 3 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
- 3 ft
- Growth rate
- Moderate
- Growth form
- Single Crown
- Shape
- Erect
- Lifespan
- Moderate
- Active growth period
- Spring and Summer
Light and water
- Shade tolerance
- Intermediate (sun to part shade)
- Moisture use
- High water use
- Drought tolerance
- Low
- Tolerance of waterlogged soil
- High
- Precipitation range
- 32 to 50 in per year
Soil
- Soil textures
- Medium and fine
- pH range
- 5.8 to 7
- Lime (CaCO₃) tolerance
- Low
- Salinity tolerance
- None
- Fertility requirement
- Medium
- Minimum root depth
- 8 in
Climate
- Minimum temperature
- −28°F
- Estimated cold hardiness
- Zone 4b and warmer
- Minimum frost-free days
- 110
- Fire tolerance
- High
Flowers, leaves and fruit
- Flower color
- Red
- Showy flowers
- Yes
- Bloom period
- Late Spring
- Foliage color
- Green
- Showy in fall
- No
- Keeps leaves
- No
- Fruit color
- Brown
Other
- Toxicity
- None
- Nitrogen fixation
- None
- Nursery availability
- Routinely Available
- Family
- Polemoniaceae
- PLANTS symbol
- PHGL4
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
- Phlox glaberrima (PLANTS symbol PHGL4).
- 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