Wisterias take up a lot of space, and when they bloom in the spring, they create an exceptionally beautiful view. However, many homeowners and gardeners have trouble getting their wisteria to bloom.
There’s a plethora of reasons why your wisteria isn’t blooming, ranging from bad care to lack of pruning.
To figure out how to get wisteria to bloom and paint a sky of flowers in your garden, you have to identify these issues and solve them.
Why Won’t My Wisteria Bloom?
Some people panic if their wisteria doesn’t bloom immediately after planting – it’s very uncommon for wisteria to bloom less than two years after planting. They take a few years to reach maturity, and you shouldn’t worry if your wisteria isn’t blooming that early.
If your wisteria isn’t blooming three years after planting, though, there could be something preventing its development. This could be a consequence of a harsh winter (check the section on wisteria care to see what’s the best way to care for your wisteria in the winter).
Another possibility is too much nitrogen in the fertilizer you’re using. Adult wisterias need to be fertilized with a fertilizer rich in potassium and phosphorus, but poor in nitrogen.
Finally, your wisteria may simply not be mature yet. Some wisteria varieties mature a few years after planting, others can take an entire decade. Make sure to check this before you choose your variety.
The most important thing to keep in mind about your wisteria is that it only blooms on new growth – this is the key bit of information if you’re wondering how to get wisteria to bloom.
To ensure your wisteria blooms, you have to prune it. By pruning, you’re removing old growth, and the plant will automatically start growing new wood and bloom once again.
How To Get Wisteria To Bloom
You should prune your wisteria in late winter. Leave only a few buds on each stem, and in the spring, new growth will emerge from these buds.
When your wisteria starts growing in the spring, it will bloom from these new buds.
It’s also possible that your wisteria isn’t blooming for some other underlying reason. In that case, you can give it a bit of a boost.
Wisterias have very thick, powerful roots. These roots spread for several feet around the center of the plant, and you can use them to force your wisteria into blooming.
Grab a shovel and dig up the soil about 1.5 feet away from the center of your wisteria. When you uncover the roots, slice them open with the shovel.
Do this to about half of the roots and the wisteria will start rapidly flowering as it starts fighting to survive.
The catch is – you’re never really putting your wisteria in any danger. Their roots are extremely long and they spread easily, which is why wisteria is often seen as an invasive plant.
The plant will ‘think’ it’s in danger, and to try and save itself (and reproduce while it still has time), it will start aggressively blooming. However, you won’t actually hurt the plant at any point.
While this trick is neat and effective, only use it if everything else has failed (pruning, changing fertilizers, etc.).
How To Care for Wisteria To Ensure A Full Bloom
Properly watering, fertilizing, and protecting your wisteria from the cold is just as important as pruning it when it comes to how to get wisteria to bloom.
Here are the most important things to remember.
Wisteria Winter Care
Although your wisteria can usually handle the winter on its own in zones 4 through 9, it’s going to need a little bit of help if the winter is particularly harsh.
Adding mulch to the base of the wisteria is a good way to keep it from completely freezing. A 5-inch layer of mulch will provide insulation to the roots, which is the most important part of the plant in the winter.
The vines don’t need any protection themselves, but you can wrap them in a thin layer of newspaper if you’re really worried about them. This can be a lot of work, though, because wisteria vines can spread over hundreds of feet.
Finally, feed your plant before it goes dormant. Fertilize it generously during the fall, while it’s still actively taking in nutrients.
Speaking of fertilizer…
If grown in an ideal environment, your wisteria won’t need fertilization. Fertilizing them once a year definitely won’t hurt them, but it’s definitely not necessary.
However, there are a few instances in which you should fertilize your wisteria. Young wisterias need fertilization to promote growth, as well as wisterias grown in pots.
Fertilizing can be especially helpful if you’re growing your wisteria in nutrient-poor soil – you’ll need to fertilize the plant to compensate for the nutrients the soil is missing.
If you need to fertilize your wisteria, use fertilizer rich in phosphorus and potassium, and follow the instructions on the packaging when fertilizing.
Whatever you do, don’t buy nitrogen-rich fertilizer – nitrogen will cause the wisteria to grow foliage, but not flowers, which will leave your wisteria bloomless.
Just like with fertilizers, wisterias need water when they’re young and still establishing themselves, but not when they’re mature. Mature wisterias only need water if the weather is very dry and hot.
If that happens, water your wisteria plentifully once a week. The soil should be moist, but never soggy.
It’s also smart to water it thoroughly before winter. This will help the roots soak up the maximum amount of nutrients before the plant goes dormant in the winter.
Wisterias need at least 6 hours of light a day to bloom well. This is why they should be kept away from other plants and shaded areas.
Ideally, your wisteria should get more than 8 hours of sunlight a day.
So, How Do You Get Wisteria To Bloom?
The most common cause of a non-blooming wisteria is the lack of pruning – they absolutely have to be pruned in order to bloom. It’s also possible that your wisteria is simply too young to bloom and you need to give it more time.
Other less likely reasons for the lack of bloom are overfertilization with nitrogen-rich fertilizers, improper winter care, or the lack of sunlight and water!