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Herbaceous Perennial

Kniphofia caulescens 'Oxford Blue'

caulescent red-hot poker 'Oxford Blue'

An herbaceous perennial reaching approximately 60cm in height when in flower with blue, spiky, glaucous leaves and spikes of tubular, orange and yellow flowers that appear in summer to autumn

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Ultimate height

1–1.5 metres

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Loam

Sand

Moisture

Moist but well–drained, Well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

South–facing or West–facing

Exposure

Exposed or Sheltered

Drought resistance

Yes

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)

Botanical details

Family: Asphodelaceae
Native to GB / Ireland: No
Foliage: Evergreen
Habit: Clump forming, Columnar upright
Genus: Kniphofia may be evergreen or herbaceous perennials, with linear or strap-shaped leaves and erect stems bearing a dense raceme of tubular, usually pendent flowers
Name status: Accepted

How to grow

Cultivation

Grow in full sun and fertile, moist but well-drained soil that isn’t too wet over winter. See kniphofia cultivation for further advice

Propagation

Propagate by division of established clumps in late spring or by taking offshoots from the crown

Suggested planting locations and garden types

Architectural
City and courtyard gardens
Coastal
Cottage and informal garden
Gravel garden
Flower borders and beds

Pruning

Cut down old flower stems after flowering; old or dead leaves can be tidied up or removed in mid-spring

Pests

May be susceptible to aphids, thrips, slugs and snails

Diseases

Generally disease-free

Get involved

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