Wisteria

Wisterias are beautiful twining climbers with beautifully scented flowers in shades of white, 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 Both 9m (28ft) or more
Aspect Full sun
Hardiness Fully hardy
Difficulty Moderate

Cultivation notes

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 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 35g per sg m (1oz 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 standard. This is particularly suitable for a small garden. See the advice profile on pruning and training wisteria for more information on container cultivation.

Containerised wisterias can be fed with liquid tomato fertiliser, phostrogen, miracle grow 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. 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, and layering is usually best for home gardeners.

Cultivar Selection

Some wisterias produce flowers before leaves, which can look spectacular in spring.

Wisteria sinensis produces its flowers before the leaves appear and has stems that twine anticlockwise. Wisteria floribunda bears leaves and flowers at the same time and has stems that twine clockwise. For a general list of great wisterias, see our RHS Plant Selector. Here are a few;

Links

RHS Plant Finder
AGM plants

Problems

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
  • 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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