Tree · Ulmaceae
Rock elm
Ulmus thomasii
Rock elm is recorded as native to 16 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 221 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
Rock elm at a glance
- Native in
- 221 counties, across 16 states and territories
- Estimated cold hardiness
- Zone 2b PLANTS minimum temperature −46°F
- Mature height
- 90 ft PLANTS mature height
- Light and water
- Sun to part shade High water use
Estimated cold hardiness: zone 2b. PLANTS gives a minimum temperature of −46°F; zone 2b winters bottom out at −45°F, the coldest half-zone that stays within that limit.
Rock elm is recorded as native to 16 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 221 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 221 where it is listed.
Native counties by state
- Arkansas 5 counties
- Illinois 10 counties
- Indiana 30 counties
- Iowa 5 counties
- Kansas 1 county
- Kentucky 15 counties
- Michigan 25 counties
- Minnesota 23 counties
- Missouri 10 counties
- Nebraska 3 counties
- New Jersey 1 county
- New York 32 counties
- Ohio 11 counties
- Tennessee 15 counties
- Vermont 5 counties
- Wisconsin 30 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
- Tree
- Duration
- Perennial
- Mature height
- 90 ft
- Growth rate
- Moderate
- Growth form
- Single Stem
- Shape
- Erect
- Lifespan
- Long
- 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
- None
- Precipitation range
- 22 to 60 in per year
Soil
- Soil textures
- Coarse, medium and fine
- pH range
- 4.5 to 7.2
- Lime (CaCO₃) tolerance
- Medium
- Salinity tolerance
- None
- Fertility requirement
- Medium
- Minimum root depth
- 40 in
Climate
- Minimum temperature
- −46°F
- Estimated cold hardiness
- Zone 2b and warmer
- Minimum frost-free days
- 120
- Fire tolerance
- Medium
Flowers, leaves and fruit
- Flower color
- Yellow
- Showy flowers
- No
- Bloom period
- Mid Spring
- Foliage color
- Green
- Showy in fall
- No
- Keeps leaves
- No
- Fruit color
- Brown
Other
- Toxicity
- None
- Nitrogen fixation
- None
- Nursery availability
- No Known Source
- Family
- Ulmaceae
- PLANTS symbol
- ULTH
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
- Ulmus thomasii (PLANTS symbol ULTH).
- 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