Wisteria

Wisterias are beautiful twining climbers with beautifully scented flowers in shades of white, blue, purple and pink. Wisteria is ideal for training into trees and covering walls, pergolas and other garden structures.

Wisteria  flowers

Quick facts

Common name Wisteria
Botanical name Wisteria
Group Deciduous climber
Flowering time April to June
Planting time Spring or autumn
Height & spread 9m (28ft) or more
Aspect Full sun
Hardiness Fully hardy
Difficulty Moderate

Cultivation notes

Wisterias are deciduous, twining climbers, native to China, Japan and the eastern United States. Of the ten species the three most commonly grown are Wisteria floribunda (Japanese wisteria), W. sinensis (Chinese wisteria) and W. brachybotrys (silky wisteria), and their cultivars. All three species are strong-growing and are capable of reaching a height of around 10m (30ft) in trees or a spread of up to 20m (60ft) or more against a wall.

Wisterias flower in the spring with occasional summer flowers. Most begin flowering within 3-4 years of planting. After a long summer, established wisterias may form pendant, bean-like seedpods that are an additional feature.

Wisteria prefers a sunny position, but can be grown in slight shade. Plant in a well-drained, fertile soil.

If buying a new wisteria, always choose one that has been grown from cuttings or by grafting. Seed raised wisterias flower less reliably, and also take longer to flower. Grafted plants can be detected by the visible bulge of the graft union near the base of the stem. Named cultivars are almost always grafted, whereas species plants may not be.

Plants will dry out quickly, especially in a light or sandy soil, so keep plants well watered, particularly when newly planted and during dry periods.

Feed in the spring, with Growmore or Fish, Blood and Bone at the rate recommended on the packet. In sandy soils (which may have low potassium levels), also apply sulphate of potash at 20g per sq m (1/2oz per sq yd). You could also use rose or flowering shrub fertilisers.

Container cultivation

Wisterias are usually thought of as climbers, but you can grow wisterias in containers, and train as a free-standing standard. This is particularly suitable for a small garden.

Use a quality loam-based potting compost such as John Innes No 3. Containerised wisterias can be fed with liquid tomato fertiliser, Phostrogen, Miracle-gro or similar flowering plant foods. Mixing controlled release fertiliser granules into the compost is another alternative.

Pruning and training

Wisteria has a reputation of being complicated to prune, but it really isn’t. Regular pruning consists of shortening new growth firstly in August and again in February. See our page on pruning wisteria for more detail.

By taking the time to prune your wisteria, you will be rewarded with a much-improved flowering display.

Propagation

Seed-raised wisterias can take up to 20 years to flower, so increase plants by layering, taking softwood cuttings in spring to midsummer, or hardwood cuttings in winter.

Professional nurserymen generally propagate wisteria by grafting, but layering is usually the most reliable method for home gardeners.

Cultivar Selection

Wisteria sinensis produces its flowers before the leaves appear, which can look spectacular in spring, and has stems that twine anticlockwise. W. sinensis is the species most suitable for walls where its shortish racemes are displayed to advantage.

Wisteria floribunda bears leaves and flowers at the same time and has stems that twine clockwise. It has the longest racemes of all the species and is shown to best effect on garden structures such as pergolas where the racemes can hang free, unimpeded by branches or foliage.

Here are a few of the most popular wisterias;

  • Wisteria brachybotrys 'Shiro-kapitan' AGM – short racemes of pure white flowers
  • W. brachybotrys 'Showa-beni' AGM – short racemes of strong pink flowers
  • Wisteria 'Burford' AGM – lilac blue and purple flowers in racemes up to 90cm (3ft) long
  • W. 'Caroline' – blue-purple flowers in dense racemes to 30cm (1ft) long
  • Wisteria floribunda ‘Alba’ AGM – white flowers in racemes to 60cm (2ft) long
  • W. floribunda 'Domino' AGM – blue-mauve flowers in racemes to 20cm (8in) long, often flowering from a young age
  • W. floribunda 'Kuchi-beni' (syn. W. 'Lipstick') – purple-tipped mauve-pink flowers in racemes 35-46cm (14-18in) long 
  • W. floribunda 'Lawrence' AGM – pale blue-mauve flowers in racemes 30-50cm (1ft-20in) long
  • W. floribunda ‘Multijuga’ AGM – lilac blue flowers in racemes up to 1.2m (4ft) long
  • W. floribunda 'Rosea' AGM – pale rose flowers tipped with purple in racemes to 60cm (2ft) in length
  • W. floribunda 'Royal Purple' AGM – deep violet-purple flowers in racemes 45-60cm (18in-2ft) long
  • W. floribunda 'Violacea Plena' (d) AGM – deep violet-purple, double flowers in racemes 30cm (1ft) or more
  • W. floribunda 'Yae-kokuryu' (d) – dark purple, double flowers in drooping racemes to 50cm (20in) long
  • Wisteria frutescens 'Amethyst Falls' (PBR) – a compact species from North America, dense clusters of lilac-blue flowers, good for large containers 
  • Wisteria sinensis AGM – lilac blue flowers in racemes 30cm (1ft) long
  • W. sinensis 'Amethyst' AGM – violet blue flowers with a reddish flush in dense racemes to 30cm (1ft) long 
  • W. sinensis 'Prolific' AGM – lilac-blue heavy racemes to 30cm (1ft) long, often flowering from a young age

Links

RHS Find a Plant
AGM plants

Problems

For an overview of wisteria problems, see our page on frequently asked questions.

Poor flowering

The most common problem gardeners have with wisteria is poor flowering. This can be caused by a number of reasons, including:

  • Young plants grown from seedlings can take 20 years to flower, so avoid disappointment by either buying a plant while it is in flower or choosing a named cultivar
  • Check your pruning technique and timing - pruning in early and midsummer will disrupt the formation of flowers for the following year 
  • Look for shredded flowers or teeth marks as tell-tale signs of bird, mice or pigeon damage
  • Take care to water in dry spells between July and September, when flower buds are forming for next year, as drought at this time can result in failure to bloom
  • Be aware that sharp spring frosts can damage developing flowers, causing them to drop before they open, or to develop in a distorted fashion
  • Wisteria flower best in full sun – excess shade is detrimental
  • On poor soils, potassium may be lacking so try applying sulphate of potash in spring to promote flower bud formation

Other problems

Sometimes a mature and apparently healthy plant will suddenly die and be replaced by a new shoot growing from the ground. This appears to be caused by wisteria graft failure.

Less common is attack by root fungi like honey fungus or Phytophthora root rot, but wisteria is susceptible to both of these.

Wisterias are also prone to scale insect infestation and may, more rarely, suffer from wisteria scale.

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