Lupinus arboreus 'Blue Boy'

RHS Plant Profile

tree lupin 'Blue Boy'

Shrubs

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Bushy semi-evergreen shrub about 1.5-2m tall, with silky stems and palmate grey-green leaves composed of leaflets 6cm long. In late spring and summer produces dense racemes to 30cm long of fragrant, pea-like blue flowers

Position

Full sun, Partial shade

Soil Types

Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1.5-2.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Loam Sand

Moisture: Well–drained
pH: Acid or Neutral

Position

Full sun Partial shade

Aspect: South–facing or West–facing or East–facing
Exposure: 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): H4

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Fabaceae
Native to GB/Ireland: No
Foliage: Semi evergreen
Habit: Spreading branched
Potentially harmful: Harmful if eaten. Wear gloves and other protective equipment when handling. TOXIC to pets if eaten (dogs, cats, rabbits, tortoises) - see the HTA guide to potentially harmful plants for further information and useful contact numbers
Genus: Lupinus can be annuals, perennials or shrubs, with palmate leaves and showy terminal racemes of pea-like flowers
Name Status: Unresolved

How to Grow

Cultivation

Grow in light and slightly acid, well-drained or sandy soil in full sun or light shade. See lupin cultivation

Propagation

Propagate by seed in early to mid-spring, softwood basal stem cuttings in mid to late spring

Suggested planting locations and garden types

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

Pruning

Deadhead to encourage a second flush of flowers

Pests

May be susceptible to lupin aphid, slugs and snails

Diseases

May be susceptible to lupin anthracnose, Powdery mildews and a virus