Quercus robur (Fastigiata Group) 'Koster'

RHS Plant Profile

oak 'Koster'

Other common names

oak 'Fastigiata Koster'

Synonyms

Quercus robur 'Kosteri Fastigiata'
Quercus robur 'Fastigiata Koster'
Quercus robur f. fastigiata 'Koster'

Trees

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A fastigiate form with upright branches, spreading with age to ultimately reach approximately 20m high and 3m wide. Usually seed-raised so can be variable. Leaves are dark green with shallow lobes

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

Higher than 12 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity: more than 50 years
Max Spread: 1.5-2.5 metres
Max Height: Higher than 12 metres

Growing Conditions

Clay Loam Sand

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

Position

Full sun Partial shade

Aspect: West–facing or East–facing or South–facing or North–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): H6

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Fagaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Columnar upright
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: Accepted

How to Grow

Cultivation

Grows well in most deep, fertile soils and is lime tolerant

Propagation

Propagate by seed, sown as soon as ripe, in a cold frame

Suggested planting locations and garden types

Cottage and informal garden
Low Maintenance

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