Wisteria floribunda 'Issai-naga'

RHS Plant Profile

Japanese wisteria 'Issai-naga'

Climber Wall Shrub

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Large, vigorous, deciduous climber about 9m tall, with twining stems, and green leaves divided into leaflets, that turn butter-yellow in autumn. Drooping racemes to 30cm long, of scented, pea-like, mauvish-blue flowers, marked violet-mauve, produced in late spring, often followed by bean-like velvety, blue-grey seed pods 15cm long. Free-flowering from a young age

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

8-12 metres

Max Spread

wider than 8 metres

Size

Time to Maturity: 10–20 years
Max Spread: wider than 8 metres
Max Height: 8-12 metres

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid or Alkaline 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): H6

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Fabaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Climbing
Potentially harmful: Harmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten - for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus: Wisteria are vigorous woody climbers with twining stems bearing pinnate leaves and long pendulous racemes of fragrant pea-like flowers in spring and early summer
Name Status: Accepted

How to Grow

Cultivation

A large, long-lived climber so choosing the right site is important. Can be grown informally through large tree or more formally against a house wall. Will grow in most soils that are moist but well-drained in sun or part shade. See wisteria cultivation for more advice

Propagation

Propagate by layering in spring, softwood cuttings from late spring to early summer, hardwood cuttings in winter, root cuttings in late winter or grafting in late winter

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Climber and wall shrubs
Wall side borders

Pruning

Prune twice a year for best results, see pruning wisteria for detailed advice

Pests

May be susceptible to aphids, glasshouse red spider mite, and scale insects including wisteria scale

Diseases

May be susceptible to honey fungus (rarely), phytophthora root rot, coral spot, fungal leaf spot, virus diseases, and powdery mildews