Instantly recognizable, the long, hanging blue flowers of the wisteria are a highlight of spring, sometimes blooming as early as March in the south, or May in the north. A good specimen in bloom is a glorious thing to see, and the full, mid-green foliage is attractive through the summer too. But this is a plant that is often also seen as a tangled jungle, engulfing everything around it, and many gardeners become frustrated with this ‘garden gangster’ and tear it out, swearing never to let another one through the gate. If there is one plant where it pays to know what you are doing, and even more importantly to know what you are planting, it is the wisteria. Gardeners in cooler areas often wait in vain for many years, puzzled by the absence of blooms, while others gaze at plants full of bloom in summer – in other people’s gardens – and wonder why theirs isn’t doing the same thing.
A while ago we devoted a whole blog to training and trimming a wisteria, but here we are going to look at the different types available, to help you make the right choice A big part of the ‘wisteria problem’ is thinking that there is just one plant called ‘wisteria’. No, there are several wild species, and even more importantly for gardeners, a number of selected varieties, with very different qualities. It’s important, if you are considering growing one – or thinking of replacing an unsuitable one – to understand the differences, which are not obvious at all when looking at a twining leafy plant.
What is Wisteria?
The plant group called Wisteria by both gardeners and botanists is a small one, with just a handful of different species in it, growing all across Asia and North America. It is part of the very large pea family of plants, which can be seen in the characteristic form of the flowers, even if the rest of the plant is not very ‘pea like’. They are naturally twining plants, with long stems that wrap themselves around anything they encounter – tree limbs in the wild, but fences, pergolas and trellis in the garden. It is possible, with training, to grow a free-standing, tree-like wisteria, but usually you need a strong supporting structure, big enough to carry what is often a large plant, that develops tree-like stems in time. The flowers vary in color from purple to sky blue, and there are white varieties too. Individual flowers are small, but they are clustered in long, hanging bunches between 6 inches to 12 inches long, on the bare branches, or among the foliage. Because they look very similar in leaf, many people don’t realize there are different wisteria, with different characteristics and abilities – the flower in colder areas, for example.
Chinese Wisteria (Wisteria sinensis)
This is the Chinese, or common wisteria, and it grows into a very large vine, reaching 50 feet or more. This is the plant that has given wisteria its bad reputation, both for size and failing to flower. If you have a very large space to fill, and don’t mind big pruning jobs a couple of times a year, then it can be very beautiful indeed, flowering on bare wood, with no leaves distracting from the display, and often with foot-long flower bunches. It only blooms on old branches, and the flower-buds are sensitive to cold. Only in zone 7 or warmer is it a reliable bloomer, so in colder zones this is not the plant for you. In areas where it does flower well it has often escaped from gardens, and it is considered an invasive alien plant across much of the south-east.
Japanese wisteria (Wisteria floribunda) is a smaller plant, but it also needs warmer zones to bloom reliably. It blooms with the new leaves, not before them, and for those who love small things, It can be distinguished from Chinese wisteria because the stems of Japanese wisteria twine in a clockwise direction, while the Chinese plant they twine counter-clockwise.
Kentucky Wisteria (Wisteria macrostachya)
Many people will be surprised to learn that America has its own wisteria – but it does. Called either Wisteria macrostachya. Wisteria frutescens, or even Wisteria frutescens var. macrostachya – they are the same plant – this plant grows wild from Kentucky, Illinois, Missouri and Oklahoma south into Louisiana and Texas. Although growing wild in warmer areas, this is the plant to choose if you live in colder areas, because it blooms reliably even in zone 4. Although it is a smaller plant, that is a relative term with wisteria, and it can still cover a 25-foot pergola or wall. Still, it is a lot more manageable than Chinese wisteria, and a much better choice for most gardens. The secret to its blooming in cold areas is that it blooms on new stems, not only on old ones, so it flowers after the leaves appear, and some continue to produce blooms in spurts over the summer.
There are several excellent varieties of the Kentucky Wisteria, with good flower color, longer flower clusters, and greater reblooming. Here are the best ones:
Often blooming three times between spring and fall, ‘Blue Moon’ has flower clusters a full foot long, with almost a hundred blooms in each one. It makes a wonderful display, and the flowers are sky-blue, with perhaps the faintest hint of lilac. This is also the hardiest form, and it can bloom even in zone 3, planted in a warm, sheltered place.
We don’t know who Aunt Dee was, but she had good taste in wisteria. This plant has 8 to 12-inch flower clusters, in lilac-blue, and it often re-blooms throughout the summer.
We do know who ‘Betty Tam’ was, which is the formal name for the variety usually called Lavender Falls. She was the wife of Patrick Tam, from Tulsa, Oklahoma, who had this plant growing in his garden for 40 years, from a seedling he raised in 1950. Only then, when he really knew it was a reliable reblooming variety, did he patent it. Now there is a cautious and thorough person! Not only does it always rebloom, this variety has attractive lavender-blue flowers, with a noticeable ‘two-tone’ difference in shade between the upper and lower petals of each flower.
This variety has beautiful purple-blue flowers, and it can be relied on to bloom both in spring and summer. It has the added advantage of blooming even when young, so you won’t be waiting years for the first blooms, as you have to with a Chinese wisteria.
So if you want to grow wisteria, we recommend you plant one of the Kentucky Wisteria varieties, and enjoy blooms several times a season, on a much more manageable plant. There! That’s everything you need to know about Wisteria.
***If you want to check the availability of any of the plants mentioned here, go to our Home Page, click on the ‘Search’ button in the upper right, and type in your choice – both common names and botanical ones will work. If, sadly, you find the item sold out, click on the ‘notify me’ box beside the size you want, and you will get an email the moment that plant is available again – it’s easy.