A woman in London recently asked me a query about her wisteria, which hadn’t flowered in 20 years. Along with “How and when do I prune it,” this is a topic that is frequently asked, so I thought I’d expand on my response to her here for the benefit of everyone.
Wisteria refuses to bloom for three causes, including a lack of sunlight, improper pruning, and inadequate nutrients.
Four, actually, if you include “Wisteria produced from seed takes 20 years to flower, so save your time by buying one in a container instead, preferably one that is already in bloom so you can predict what color it will be.”
Nutrition: Let’s start with the most straightforward one first. If the plant has been there for a while, especially if it is planted close to a wall and has been there for a while, it may be starting to run low on nutrients. Throughout the summer, I would advise giving it a tiny fistful of bone meal to spread around the main stem, work into the soil, and then water in.
In the late summer or early fall, you may also give it a feed of something like Tomato Feed, diluted exactly as directed on the package. This will encourage it to produce blossoming buds for the following spring, at least theoretically.
After blossoming in the late spring, should you feed it tomato fertilizer every two weeks? Personally, I don’t think so, but since many others advise it, why not give it a try? Just remember to properly dilute it; there is no benefit to giving it a “double dose” (*wags finger in a warning*).
Sun: If wisteria do not receive enough sun, they will not bloom. This indicates that they should be located on a south-facing wall, which is one where you are facing south if you stand with your back to the wall.
One will never bloom if it is put against a wall that faces north. If it is west-facing and receives a lot of late afternoon sun, you might be in luck. East-facing: You’ll never receive more than a few scant flowers. You have two choices if you discover that your non-flowering Wisteria was planted in the incorrect location: either dig it up and start over, or if you’re lucky, train it to grow around the corner to the south-facing wall.
I had a client who had exactly similar issue; they had planted wisteria on a west-facing wall that was heavily shaded in the hopes that it would bloom all over the house. Given that the house’s corner was available, I installed some wires on the south-facing wall and trained the strongest long, whippy shoots to follow the new wires around the corner. They are beautifully bulking up, and I’m expecting for flowers this year or even the following. The blossoming wood needs to be in the sun, but the plant’s roots don’t.
It’s important to note that even if your plant is on a south-facing wall, it won’t bloom if it is significantly shaded by nearby trees, other structures, etc. If trees are the issue, you might be able to elevate their crowns or thin their canopies to let in more light.
Pruning: Ah, yes, the pruning debate. Right. It’s very easy. Your wisteria will start to produce dozens of long, thin, bright green, whippy shoots in the early summer each year. Just 2 or 3 leaves should remain after pruning them. Since they keep sending out more no matter how much you prune off, I do this trimming probably three or four times throughout the summer. I advise you to take the secateurs outside once every three to four weeks and cut them off.
Winter pruning is cutting back all those shortened young shoots, which are now brown and lifeless, to just one or two buds after it has done developing and lost its leaves. Shake out any clumps of dead leaves entangled in the branches and remove all the spindly, dead stems you can locate. You should try to leave behind a sturdy stem foundation.
This is how your wisteria should seem if you have ever seen an authentic old vine. thick stems with twisted clusters of knobs. These are the buds that will bloom. So, go over your plant and remove every teeny, little stem.
You shouldn’t have too much work to do in the winter if you get outside now and complete the summer pruning. You will have more to accomplish in the winter if you simply can’t find the time to complete it now.
When I do this later in the year, I’ll take pictures so I can eventually provide a step-by-step instruction.
Pruning has three points:
1) Don’t let all the whippy stems grow if your wisteria isn’t quite big enough in the hopes that “it will swiftly cover up the pergola/trellis/building.” Select a small number of the whippy stems, and then neatly tie them to the support. These few will form the “framework of sturdy stems” for your design. If you can, arrange them on parallel wires or in a tidy fan shape. Although this may seem like a sluggish beginning now, it will pay off in the long run.
2) The actual cut: Just a friendly reminder, whenever you prune something, try to make a straight cut that is angled away from the bud you are removing. Reasons:
A ragged cut invites infection, so maintain your tools sharp and make precise cuts. Get the loppers if the branch is too thick for your secateurs!
b) If you leave a reasonably long piece of stem above a bud, it will wither away since the plant’s energy will reach the bud and stop there. It can be terrible for the plant if a stem begins to die back because it usually continues to do so.
c) sloping the cut lowers the chance of rotting by allowing rain and dew to slide off the cut and away. The blossom will catch all the water and perish if the cut is angled in its direction.
If you’re not sure, search “pruning cut” in Google and select “Images,” where you’ll find dozens of examples. You might benefit from some private instruction if you really can’t get the hang of it; click the page icon more information. Ask a friend or neighbor to show you how if you are not in South Oxfordshire.
3) If it’s a large wisteria, you exclaim, “How do I reach up there?” Purchase a pruning pole with a long handle for an easy solution. A few of my elderly clients have great old wooden ones, while I have a lovely lightweight aluminum one that allows me to reach first floor windows. In essence, they are merely poles with knives or other blades on the ends, along with a handle or rope to operate the blade. With these instruments, you obviously don’t achieve quite the finesse — for example, you can’t make a perfect slope cut when working 8′ above your head — but it does mean that you can do the task yourself and avoid using ladders.
Additionally, it demonstrates that even though it is Best Practice to make a sloping cut immediately above a bud, pruning should still be done.
Wisteria floribunda, or Japanese Wisteria, and Wisteria sinensis, or Chinese Wisteria, are the two varieties.
Sinensis or Chinese: if you imagine yourself standing at the base of the stem and looking upwards, the flowers emerge before the leaves do.
Japanese or floribunda wisteria has leaves and flowers that bloom at the same time, a raceme that is much longer than Chinese wisteria’s, and stems that twine in a clockwise direction.
Now that you know, good! By the way, both of them are moderately poisonous throughout, but especially in the seeds, which are seductively velvety when young. As always, and I’m sure you’ve heard me say it before, TEACH YOUR KIDS THAT FOOD SHOULD ONLY BE EATEN FROM PLATES.
Since modern kids are permitted to graze all the time, it’s no wonder that most of them are as fat as little pigs, ha ha! But the garden is full of numerous deadly plants. I frequently receive requests from overly concerned parents for lists of plants that are not toxic, and I have to explain to them that it is nearly hard to create a garden solely out of “safe” plants.
You may not be aware, but daffodils are toxic. Columbine, too? Crocus? Buttercup? Box? Bindweed? Beech? Chickweed? Laurel? Delphinium? Ground Ivy? Hellebores? Holly? Ivy? Iris? Laburnum? The Lily of the Valley? Larkspur? Oak? How many alphabetical letters do you want me to read through?
Teaching your kids not to consume anything that isn’t on a plate is far preferable.
I’m aware that there’s a trend to encourage adults to cultivate their own herbs and vegetables, and headlines about it always include smiling little kids holding a tiny carrot or strawberry on the verge of their mouths. Occasionally, not even an adult in view. Given that so many plants are poisonous, I shudder at the thought. Take the young kids to the vegetable garden or the allotment, but instruct them to bring back the edibles to you, the adult, so you may check them, wash them if necessary, and arrange them on a plate for eating.
Will wisteria flourish on a wall that faces northeast?
For growing this most magnificent of horticultural spectacles, Alan Titchmarsh offers tips.
There are several benefits to spring arriving slowly. After a bitterly cold, rainy, and snowy winter, when army-blanket skies were the norm week after week and month after month, it is disheartening to have to wait so long for flowery joys.
Late springs, on the other hand, lessen the possibility of early development, which can frequently be severely scorched by late frosts. Due to unanticipated freezing conditions at the end of the month, a friend’s wisteria, which had put on a stunning annual display for fifty years, was dripping with depressing, grey flower trails in April last year.
Given that the buds didn’t even begin to open until the middle of April, they had high expectations for the kind of show that has become synonymous with their home this year.
How much I adore wisteria! When we got married, it graced the front wall of our humble three-up, three-down terrace house. I trained it with pride so that, during the six years we lived there, its territory grew year after year.
It was the common Chinese wisteria (W. sinensis), which for a long time was the only kind to grow in our gardens. Numerous cultivars with weird names and, in certain cases, strange colors and flower forms are available today, the majority of which are of Japanese origin.
At the Kawachi Fujien Wisteria Garden in Kitakyushu, Fukuoka, Japan, a wisteria tunnel is in full bloom.
If you’re planting a new one, make sure you like the color and blossom shape before purchasing a grafted plant because it will bloom more consistently and much earlier. A few inches above soil level, the graft union will be readily evident. There are strategies to induce blooming in older reticent plants, including those that weren’t grafted and were reproduced by layering or cuttings.
You need a sunny wall for wisteria. Giving it a wall with a north or east facing side is a waste of time. The most favored directions, where the wood will ripen most efficiently, are south and west. The pruning process itself is done twice a year. All questing growths that are required to increase the plant’s coverage should be tied in by July; all others should be cut back to around 1 foot. All sideshoots should be pruned to finger length in January. If you repeat this each year, your plant shouldn’t let you down.
Gorgeous Lodge House in Smeeth, Kent, close to Ashford, has a Georgian front covered in thick wisteria.
Wisteria is a twiner and doesn’t have sticky pads like Virginia creeper or aerial roots like ivy, so your wall will need some sort of support system. The least noticeable support is provided by strong horizontal wires attached to strong vine eyes screwed into the wall at intervals of 18in.
The likelihood of this happening can be reduced by regularly untangling the stems during winter trimming. A well-attached trellis can be used, but the snaking branches can get behind it and, as they fatten over the years, they can rip it from the wall.
Every March, you may encourage regular bloom and strong development by giving your wisteria a liberal serving of rose fertilizer, which is rich in potassium and magnesium, which assist flowers open up. If your wisteria has been pruned, nourished, and grown on a sunny wall for three or four years and still won’t bloom, consider it a failure, yank it out, and plant a grafted type that will catch up to it.
The wisteria-covered entrance to Dunsborough Park in Ripley, Surrey, is like the doorway to paradise.
The ancient standby Macrobotrys, which has flower trails that may reach a maximum length of two feet, is my personal favorite of the several types that are offered. The elegant white variety are just as striking as the lavender purple ones in the correct circumstances.
The plain W. sinensis, whose flower trails emit the most scrumptious aroma in spring sunshine, is a plant I would never avoid, especially if it were planted near a bedroom window that could be opened to let in the intoxicating scent.
Being so demanding with food and water, wisteria plants are difficult to grow successfully in pots and other containers. You can grow wisteria as a free-standing “standard” on a 5 foot bare stem if you don’t have access to a suitable home wall. It will require some support, but when I was a student at Kew Gardens, I recall enormous free-standing specimens there that were already well over a century old. They scuttled around a rusting iron structure that they had all but destroyed like boa constrictors.
To enjoy the pleasures of late spring and early summer in the company of one of the most stunning members of the plant world, all we need right now is the kind of sunny weather that was lacking earlier in the year.
Which wisteria does shade best?
Although the majority of wisteria plants like full sun, a shaded location is occasionally the only choice. If it applies to your garden, it doesn’t mean you can’t take advantage of one of these lovely plants. Wisteria sinensis is the ideal wisteria for shade. One of the few Wisteria cultivars with a potential for partial sun blooming is this one.
But remember that most Wisteria require full sun to bloom. You may never get to witness the magnificent sight of the plant completely bloomed if you choose to plant yours in partial sun or shade.