Wildflower (forb) · Clusiaceae
Great St. Johnswort
Hypericum ascyron
Great St. Johnswort is recorded as native to 17 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 262 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
Great St. Johnswort at a glance
- Native in
- 262 counties, across 17 states and territories
- Estimated cold hardiness
- Zone 5a PLANTS minimum temperature −23°F
- Mature height
- 5 ft PLANTS mature height
- Light and water
- Full sun (shade-intolerant) Medium water use
Estimated cold hardiness: zone 5a. PLANTS gives a minimum temperature of −23°F; zone 5a winters bottom out at −20°F, the coldest half-zone that stays within that limit.
Great St. Johnswort is recorded as native to 17 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 262 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 262 where it is listed.
Native counties by state
- Connecticut statewide record
- Illinois 26 counties
- Indiana 13 counties
- Iowa 2 counties
- Kansas 1 county
- Maine 1 county
- Maryland 1 county
- Massachusetts 4 counties
- Michigan 35 counties
- Minnesota 28 counties
- Missouri 5 counties
- New Hampshire 3 counties
- New York 20 counties
- Ohio 29 counties
- Pennsylvania 25 counties
- Vermont 8 counties
- Wisconsin 61 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
- 5 ft
- Growth rate
- Moderate
- Growth form
- Single Crown
- Shape
- Erect
- Lifespan
- Long
- Active growth period
- Spring and Summer
Light and water
- Shade tolerance
- Intolerant (full sun (shade-intolerant))
- Moisture use
- Medium water use
- Drought tolerance
- Low
- Tolerance of waterlogged soil
- Medium
- Precipitation range
- 32 to 55 in per year
Soil
- Soil textures
- Medium and fine
- pH range
- 5.7 to 7.1
- Lime (CaCO₃) tolerance
- Low
- Salinity tolerance
- None
- Fertility requirement
- Medium
- Minimum root depth
- 14 in
Climate
- Minimum temperature
- −23°F
- Estimated cold hardiness
- Zone 5a and warmer
- Minimum frost-free days
- 80
- Fire tolerance
- High
Flowers, leaves and fruit
- Flower color
- Yellow
- Showy flowers
- Yes
- Bloom period
- Late Summer
- 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
- Clusiaceae
- PLANTS symbol
- HYAS80
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
- Hypericum ascyron (PLANTS symbol HYAS80).
- 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