River birch Betula nigra
River birch (Betula nigra) is a deciduous perennial tree in the Betulaceae family, native to Eastern and southeastern United States. It grows 10–18 m (33–59 ft) tall and 8–12 m (26–39 ft) wide, wants full sun and high water, and is hardy to about -32 °C (-26 °F). Space plants about 8 m (26 ft) apart.
Plan River birch in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
River birch at a glance
| Type | Perennial tree, deciduous |
|---|---|
| Family | Betulaceae |
| Mature height | 10–18 m (33–59 ft) |
| Mature spread | 8–12 m (26–39 ft) |
| Spacing | 8 m (26 ft) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | High; drought tolerance low, waterlogging tolerance high |
| Soil pH | 4.5–6.5 |
| Cold hardiness | About -32 °C (-26 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 36 °C (97 °F) |
| Flowering | from about April for 1–3 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Low |
| Edible | Not grown as food |
| Native to | Eastern and southeastern United States |
| Common in gardens of | 🇺🇸 United States |
Is River birch toxic?
- People: not known to be toxic
- Cats: not well documented
- Dogs: not well documented
Not considered toxic to people; pet toxicity is not well documented.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with River birch
No well-documented helpful pairing. Group it with plants that like full sun and high water.
See River birch in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- Brooklyn Botanic Garden (1 plants)
- Riverside botanical garden (3 plants)
Questions about River birch
- How far apart should I plant River birch?
- About 8 m (26 ft) apart, centre to centre. A mature plant spreads 8–12 m (26–39 ft).
- Does River birch need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does River birch need?
- High water. Drought tolerance is low and waterlogging tolerance high.
- How cold-hardy is River birch?
- It tolerates about -32 °C (-26 °F) once established, roughly USDA zone 4.
- When does River birch flower?
- From about April for 1–3 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is River birch poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people not known to be toxic. Not considered toxic to people; pet toxicity is not well documented.
- What grows well with River birch?
- There is no well-documented companion pairing for River birch. Group it with plants that like the same sun (full sun) and water (high).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- Extension Gardener Plant Toolbox, NC State Extension
- USDA PLANTS Database, USDA NRCS
Notes and assumptions
- The most heat-tolerant birch and resistant to bronze birch borer; yellows (chlorosis) in alkaline soil.
- Wind-borne pollen is allergenic.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Silver birch Betula pendula
- Common hazel Corylus avellana
- European hornbeam Carpinus betulus
- Paper birch Betula papyrifera
- Mountain birch Betula pubescens subsp. czerepanovii
- Turkish hazel Corylus colurna
- Himalayan birch (bhojpatra; white-barked jacquemontii) Betula utilis
- Dwarf mountain pine Pinus mugo