Black Dragon / Kokuryu Wisteria

• Variety: Black Dragon (Kokuryū) – deep purple doubles on long racemes
• Latin name: Wisteria floribunda 'Kokuryū'
• Species: Japanese (W. floribunda)
• Flower colour: Deep purple-violet, double
• Scent: Sweetly fragrant
• Climbing method: Twining stems (clockwise)
• Height: To 9m (30ft)
• Flowering: May–June
• Grafted: Yes – flowers within 2–3 years (seed-raised plants can take 20 years)
• Hardiness: H6 – fully hardy
• RHS AGM: Yes (confirmed December 2024)
• Sold as: P9 and 3L deep pots, grafted plants. Peat-free compost
• Plant outdoors: Year-round
• Delivered: March–November typically. Collection from Castle Cary also available

Black Dragon Wisteria – Not Black, but Magnificent

We should be honest about the name. Black Dragon is not anything like black. It is deep purple, and sweetly scented, and one of the most desirable wisterias you can grow. The double flowers hang in long racemes from May to June, darker and richer than any other wisteria in our range. We have one on a pergola in the garden that has been there for more than twenty years. If we were to move and start a new garden, the first thing we would do would be to build a pergola and plant another Black Dragon. It holds an RHS Award of Garden Merit, awarded in 2012.

This is a Japanese wisteria, Wisteria floribunda, which means it twines clockwise, flowers with its leaves rather than before them (as the Chinese species does), and produces longer racemes. It is vigorous and will reach 9m on a strong support. A solid pergola, a house wall with well-anchored wires, or a substantial free-standing framework are all suitable. This is a heavy plant at maturity and needs something built to last. It is fully hardy anywhere in the UK.

The Grafting Question

Every wisteria we sell is grafted, which is the single most important thing to know when buying one. A grafted wisteria flowers within two to three years. A seed-raised plant, which is what you risk buying from general garden centres and online marketplaces, can take fifteen to twenty years, and may never flower well at all. The difference is that a grafted plant is a vegetative copy of a known, proven flowering variety; a seedling is a genetic lottery. When people tell you their wisteria has never flowered, the usual answer is that it was seed-grown.

Summer Succession After the Wisteria Finishes

Wisteria finishes flowering by late June. To keep the same wall or pergola earning its keep through summer, plant a Group 3 clematis to take over. Polish Spirit (deep purple, July to September) is the natural partner; you get a continuation of rich colour without a gap. Étoile Violette gives the same effect in a slightly different purple. For a sharp colour contrast rather than a tonal match, Bill MacKenzie clematis produces yellow bells and magnificent seedheads from August onwards. At ground level, lavender makes an excellent underplanting, and spring bulbs beneath the bare winter stems give early interest before the wisteria leafs out.

Where Your Wisteria Comes From

The wisterias we sell are among the very few climbers that we do not propagate ourselves. They come from a grower we have known for well over twenty years, a specialist who grafts to the standard we require. We are honest about this because we think it matters: we could propagate wisteria, but we would rather sell plants from someone who has spent decades perfecting the process. Every other climber in our range we raise from our own cuttings, in peat-free compost with biological controls. All our plants are guaranteed. We are a Which? Gardening Best Buy supplier and a Feefo Platinum Partner. See the full wisteria range.

Frequently Asked Questions

Why hasn't my wisteria flowered?

The most common reason is that the plant was raised from seed rather than grafted. A seed-grown wisteria can take fifteen to twenty years to flower, and some never do. All Ashridge wisteria are grafted and should flower within two to three years of planting. Other causes: too much nitrogen (high-nitrogen feeds encourage leaf growth at the expense of flowers), insufficient sun, or failure to prune. The twice-yearly pruning regime is essential for flowering. For full instructions see our wisteria pruning guide.

When should I prune Black Dragon wisteria?

Twice a year. In July or August, cut the long whippy side shoots back to five or six leaves from the main framework. In January or February, cut those same shoots back again to two or three buds. This spur-pruning concentrates the plant's energy into flower production. It takes five minutes with secateurs once you know what you are doing, and it is the difference between a wisteria that flowers and one that just grows leaves.

How long will it take Black Dragon to flower?

Two to three years from planting, because it is grafted. You may see a few racemes in the first spring if the plant is well established. By the third year, flowering should be reliable and increasing every year thereafter. Patience in the first couple of years is repaid many times over.

What is the difference between Chinese and Japanese wisteria?

Black Dragon is Japanese (W. floribunda). Chinese wisteria (W. sinensis) flowers before its leaves emerge and produces shorter racemes; Japanese wisteria flowers with its leaves and produces longer racemes. Japanese types also twine clockwise; Chinese anticlockwise. For a classic heavy-flowering Chinese wisteria, see Prolific. For the most spectacular raceme length of all, Multijuga can produce racemes to 60cm or more.

Is wisteria poisonous?

Yes. All parts are toxic, especially the seeds. Keep dogs and young children away from the seedpods. This is not a reason to avoid planting wisteria, but it is worth knowing.

How big will Black Dragon get?

To 9m in height and considerable width, given time and a strong support. Twice-yearly pruning keeps it in shape and under control. An unpruned wisteria on a pergola will eventually try to pull the pergola apart, so training and pruning are not optional. The reward for keeping on top of it is better flowering and a plant that enhances rather than destroys its support structure.