The traditional, familiar wisteria plant we all know and love has hanging, lilac or purple blooms but did you know that separate species of wisteria exist worldwide that bloom in other colours?
You can read more details below but first, let’s determine which type of trellis is best for your chosen wisteria:
1. How tall and wide will my wisteria plant climb?
The height and spread of the mature plant will decide on the strength of the trellis required. Most wisterias can grow up to 20 metres high (65 feet) and they expand to approximately 10 metres wide (32 feet 9 inches). A piece of advice though – these plants live a very long time and may outlive you.
The Guinness Book of Records has recorded the largest wisteria on the planet. It is a Chinese lavender wisteria, planted in 1894 in Sierra Madre in California in America. This mighty plant is a full acre long and weighs a staggering 250 tons.
The oldest wisteria in the UK is 205 years old, and you can view it in Chiswick, where it adorns Griffin’s Brewery. You have been warned how tall and heavy wisteria can grow!
The message is that your trellis may have to support a very large, heavy plant so it needs to be super strong. Wisteria branches twist happily around trees, walls and buildings. In fact, wisteria will attach itself to any support it finds.
2. Which type of trellis is best and how much support will my wisteria need?
Check the predicted height and spread of the wisteria you plan to grow before choosing your trellis option:
- Existing tree support. Some gardeners start with allowing a wisteria to attach itself to an available tree, but be warned that few plants can compete with wisteria.
- Next to a house wall. You can see some fabulous pictures all over the internet of wisteria-covered houses. Think carefully before you plant it this close to a building. It can become invasive so before you plant it next to your house, make sure your neighbours like it as much as you do. Wisteria is listed as an invasive plant species in temperate zones in America because the roots can cause cracks in buildings.
- Espaliered against a wall. Espaliered wisterias can be supported with galvanised steel wires (3mm is ideal). Place them about 45cm (18″) apart, which will support the growing plant well
- A climbing stake. You can grow wisteria as a free-standing tree if you have a large garden. Its initial support will be a climbing stake.
- Pot wisteria with trellis. It’s possible to grow wisteria in a large pot with a trellis, which controls its spread if space is an issue in your garden. You may need to use another option and re-pot as it grows larger.
- A free-standing pergola. Providing a sturdy pergola is perfect for wisteria to climb up and over, and you can prune it sharply to keep it in shape. See pruning below.
NOTE: It’s almost impossible to dig out an established wisteria plant, so choose your planting location carefully.
3. Sun or partial shade?
Wisteria prefers full sun but it will grow happily in semi-shade in most countries in Europe, including the UK.
Wisteria dislikes frost so if you have frost pockets in your garden, remember this when planting. Provided that your soil meets its requirements wisteria is happy in partial shade during part of the day.
The first species of wisteria to make it to the UK was Wisteria sinensis (the Chinese variety) which is native to China. In 1816, cuttings were sent back to the UK by agents of the East India Company.
From here it spread to the US, where American wisteria, Wisteria frutescens, and the Kentucky Wisteria macrostachyas now grow as native species. Wisteria floribunda (the Japanese variety) grows all over Japan and several varieties grow in Korea.
4. Soil required
Potash and phosphorous are both essential for good wisteria blooms. When you prepare the ground before planting, try to add well-rotted manure if you can, which will feed this hungry climber. Good home-made garden compost is ideal too because it is full of nutrients.
Wisteria also needs good drainage so ensure that the drainage is excellent to give the plant the best start. You can add pebbles, some sand or grit to improve drainage. You can plant in either spring or autumn. There are specialised wisteria liquid feeds available – just ensure they contain potash and phosphorous, or you will be disappointed at flowering time.
The different species of wisteria to choose from
Which direction do the stems climb?
Japanese and Chinese wisterias have one noticeable difference! Japanese wisteria twines clockwise around the host plant and the Chinese wisteria twines counter-clockwise so this is one easy way to check which variety you have.
Early or later flowers?
Early spring flowers (from April onwards) are produced in both Chinese and Japanese wisterias. Japanese wisteria flowers are also said to be more fragrant.
Later flowers on other varieties include the American wisteria and the Kentucky wisteria. These bloom in mid to late summer.
Colour of the blooms
Traditional wisteria flowers come in shades from lilac to almost purple. Wisteria floribunda ‘Royal Purple’ (Japanese wisteria) has blooms almost 20 inches long which fill the surrounding air with a delightful scent. Growers compare it to the English cottage garden favourite, the sweet pea.
In wisteria flowering season, people all over the world go crazy on Instagram, Snapchat and Pinterest. A wisteria festival takes place in Japan’s Ashikaga Flower Park every year, celebrating this gorgeous flower when it is in bloom. The festival begins when flowers start to bloom and usually lasts for a full month, providing ample photo opportunities of fabulous blooms.
More on this: Wisteria Hysteria: Growing an Instagram-Worthy Garden
However, purple flowers are not the only option for wisteria. You can choose from various shades of lilac, white, pink and blue. Mixing and matching the colours makes a spectacular display.
- Lilac. Japanese wisteria Wisteria floribunda and Chinese wisteria Wisteria sinensis have traditional lilac flowers.
- Purple varieties such as Wisteria floribunda ‘Royal Purple’ (Japanese wisteria) have long blooms, almost 20 inches long, which fill the surrounding air with a delightful, sweet pea-like scent.
- White flowers come from Wisteria floribunda ‘Alba’ which arrive in June.
- Blue flowers come from the Blue Moon variety of the Kentucky wisteria Wisteria macrostachya (Torr. & Gray), which grows up to 7 metres (almost 23 feet).
Why won’t my wisteria plant flower?
- Frost damage is the first possibility. The Chinese wisteria is very sensitive to cold so this may be the answer. Often the blooms will wither and the whole vine may be so shocked it dies back slightly. When you plant your wisteria, try to choose a warm sheltered area or alternatively, provide covered protection from frost when cold weather is forecast. Other varieties are less sensitive.
- Is it a new plant? Wisteria takes several years to become established so if your plant is less than 3 years old, don’t worry. First blooms usually appear 3-4 years after planting.
- A high potash feed can help a new plant flower.
- Lack of water. Wisterias usually appreciate some extra water between July and September. At this time of the year, the flower buds are forming. If water is scarce in a really dry period during these months, it may reduce the number of flowers the following year. So water occasionally particularly if there is a very dry period during the summer.
- Pruning at the wrong time is usually the other reason why blooms don’t arrive, so keep reading.
How do I prune wisteria?
Prune your wisteria plant well twice a year in general, once in spring and once in summer, after its first full growing season. Wisteria will lose its leaves each year so do not be alarmed when this happens.
The first prune is in spring, about February time. You will notice new buds starting at the base of last year’s branches. This is the time to trim side shoots which will cause the flowers to bunch together nicely when they flower.
The second prune is a tidy up, cutting away at overlong, leggy shoots that grew in the summer. Go back to the main branch and cut back this year’s branches so that you have 5 or 6 leaf buds remaining close to the main branch. Cut just above the last leaf.
If you feel the wisteria is too large, you may want to prune it to reduce it a little. To do this prune some shoots back about 20-40cm (7.8 -15.7 inches) long in midsummer and then again in the autumn.
Is wisteria poisonous?
Very! This is a plant to keep away from children, cats and dogs because it is really poisonous.
Children think the seed pods are like edible peas which have caused poisoning and trips to A&E. All parts of the plant are toxic and can cause vomiting, diarrhoea and nausea. Seek medical advice if a child swallows any part of wisteria.
So now you can choose a wise spot for this gorgeous cottage favourite climber and enjoy the wisteria flowers for years to come.