Quercus macrocarpa

RHS Plant Profile

bur oak

Other common names

burr oak, mossy cup oak, mossy-cupped white oak

Trees

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A large deciduous tree to 25m with green lobed leaves that turn yellow-brown in autumn before falling. The acorns can be large, up to 5cm across and the cup has long hairs in a fringe around the lip

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

Higher than 12 metres

Max Spread

wider than 8 metres

Size

Time to Maturity: 20–50 years
Max Spread: wider than 8 metres
Max Height: Higher than 12 metres

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained
pH: Alkaline or Neutral

Position

Full sun

Aspect: East–facing or North–facing or South–facing or West–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Fagaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Spreading branched
Potentially harmful: Pets (dogs): Harmful if eaten - for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus: Quercus can be deciduous or evergreen trees or shrubs, with entire, lobed or toothed leaves; flowers inconspicuous, followed by characteristic acorns; sometimes good autumn colour
Name Status: Correct
Plant Range: North America

How to Grow

Cultivation

Suited to large gardens and parkland. Grow in any well-drained but moisture-retentive soil in good light as long as it isn't too acidic. For more advice see tree cultivation

Propagation

Propagate by hardwood cuttings in autumn or by sowing seed soon after it drops. For more advice see propagating from seed (tree/shrub

Suggested planting locations and garden types

Architectural

Pruning

Pruning group 1

Pests

May be susceptible to oak processionary moth, aphids, caterpillars, leaf-mining moths and oak gall wasps

Diseases

May be susceptible to powdery mildews and honey fungus