Bur oak Quercus macrocarpa
Bur oak (Quercus macrocarpa) is a deciduous perennial tree in the Fagaceae family, native to Eastern and central North America. It grows 18–30 m (59–98 ft) tall and 15–25 m (49–82 ft) wide, wants full sun and low water, and is hardy to about -40 °C (-40 °F). Space plants about 18 m (59 ft) apart.
Plan Bur oak in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Bur oak at a glance
| Type | Perennial tree, deciduous |
|---|---|
| Family | Fagaceae |
| Mature height | 18–30 m (59–98 ft) |
| Mature spread | 15–25 m (49–82 ft) |
| Spacing | 18 m (59 ft) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance high, waterlogging tolerance low |
| Soil pH | 5–8 |
| Cold hardiness | About -40 °C (-40 °F) once established (roughly USDA zone 3) |
| Heat stress | Likely above about 40 °C (104 °F) |
| Flowering | from about May for 1–3 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | High |
| Pollinator value | Low |
| Edible | Yes: acorns (after leaching tannins) |
| Native to | Eastern and central North America |
| Common in gardens of | 🇨🇦 Canada, 🇺🇸 United States |
Is Bur oak toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: moderately toxic
- Parts: acorns, leaves
Tannins: stomach upset; risky for dogs and livestock in quantity.
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 Bur oak
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Questions about Bur oak
- How far apart should I plant Bur oak?
- About 18 m (59 ft) apart, centre to centre. A mature plant spreads 15–25 m (49–82 ft).
- Does Bur oak need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Bur oak need?
- Low water. Drought tolerance is high and waterlogging tolerance low.
- How cold-hardy is Bur oak?
- It tolerates about -40 °C (-40 °F) once established, roughly USDA zone 3.
- When does Bur oak flower?
- From about May for 1–3 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Bur oak poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs moderately toxic; for people mildly toxic. Tannins: stomach upset; risky for dogs and livestock in quantity.
- What grows well with Bur oak?
- There is no well-documented companion pairing for Bur oak. Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade A (A: strong evidence).
- VASCAN: Database of Vascular Plants of Canada, Canadensys / Université de Montréal Biodiversity Centre
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
Notes and assumptions
- Big acorns in fringed cups; corky fire-resistant bark made it the oak of the prairie savannas. Tolerates city and drought.
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
- Sweet chestnut Castanea sativa
- English oak Quercus robur
- Southern live oak Quercus virginiana
- European beech Fagus sylvatica
- Holm oak Quercus ilex
- Coast live oak Quercus agrifolia
- Cork oak Quercus suber
- Northern red oak Quercus rubra