Updated/Fact-Chacked on August 23, 2023 by Gareth James
I’ve been in my new property 3 years now with my inherited wisteria from the previous owner. I do love it, but the flowering time is so short. I keep hearing about wisteria having a second bloom in August and been looking at ways to achieve this.
Many people struggle to actually get their wisteria to bloom at all, maybe I’m just greedy. I’m hoping the high levels of love and attention will give me a second bloom this month.
Here and so things to do to encourage your wisteria to bloom if you have had no flowers; these consideration should also produce better blooms and possibly a second flush of flowers.
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Time and patience
It is important to understand that wisteria has a long juvenile period before it starts flowering. The plant can take 2-5 years to mature and produce flowers and up to 20 years if grown from seed.
The trick is not to grow wisteria plants from seeds but buy ‘grafted plants’. Grafted wisteria plants have had a piece of one wisteria plant (the scion) grafted onto the rootstock of another plant. This process is often used to bypass the long juvenile phase that wisteria plants naturally go through before they start to bloom.
Grafted wisteria plants tend to flower within a year or two of planting, as opposed to the 5-20 years it can take for seed-grown wisteria to mature and flower.
Another benefit of grafted wisteria is that they are typically more reliable in terms of the flower colour and form you can expect, as they are essentially clones of the parent plant. However, grafted wisteria plants can be more expensive than seed-grown ones due to the additional labour and skill required for grafting. You can get a good quality grafted wisteria plant for around £30 – have a look at these.
How to prune wisteria to encourage flowers?
Pruning is an essential step in encouraging wisteria to flower. It not only shapes the plant but also stimulates the development of flower buds. The pruning process should occur twice a year: once in the summer and once in the winter.
Waiting for a second bloom in August…Summer pruning
In July or August, cut back the new shoots of the current year to about 5-6 leaves. This process creates better airflow through the pant and allows sunlight to reach the remaining leave to produce energy for the remaining buds.
You also need to remove all the shoots from the base of the plant, these are trying to produce new new plants.
Here’s how my wisteria was looking before its summer prune (apologies for the poor video quality, I’ll try better next time).
Winter pruning
In January or February, cut back the same shoots to about 2-3 buds. This concentrates the plant’s energy into the remaining buds, encouraging them to develop into flowers.
Be cautious not to prune off the old wood, as this is where the flower buds form. Also, remove any unwanted or tangled growth to prevent the plant from becoming too dense, as this could hinder air circulation and sunlight penetration.
Check out Mark’s wisteria pruning video below, the wisteria on the front of his house looks amazing in bloom.
I’ve currently got a pruning nightmare as I have a clematis growing into my wisteria – poor planning by the previous owner. It’s like they have locked in a war to take over the pergola.
Good soil and correct nitrogen levels
The soil in which wisteria is planted can significantly affect its ability to flower. Wisteria prefers slightly acidic to neutral soil with good drainage. It is important to maintain a pH level of around 6-7. You can use a PH meter to check the soil’s pH and amend it accordingly with lime or sulfur.
Nitrogen levels also play a crucial role in wisteria flowering. Excessive nitrogen can encourage leafy growth at the expense of flowers. So, when you’re fertilizing your wisteria, make sure to use a balanced fertilizer or one that is low in nitrogen and high in phosphorus and potassium. Apply the fertilizer in early spring and again in mid-summer – the RHS recommends Growmore.
Feed your wisteria in spring with Growmore or Fish, Blood and Bone at the recommended rate shown on the packet. In sandy soils (which have low potassium levels) also apply sulphate of potash at 20g per sq m (1/2 oz per sq yd). You can also use rose or flowering shrub fertilisers. RHS
Correct watering
Wisteria needs regular watering, especially during dry periods. However, overwatering can lead to root rot and other fungal problems, which could affect flowering. Therefore, it’s essential to strike a balance.
Water your wisteria deeply but allow the soil to dry out between watering sessions. Use a soaker hose or a drip irrigation system to avoid waterlogging the soil. Additionally, adding a layer of mulch around the base of the plant can help retain moisture and suppress weeds.
Correct amount of sunlight
Sunlight is a vital factor for wisteria to flower. The plant requires at least six hours of direct sunlight daily to bloom properly. If your wisteria is planted in a shaded area, consider relocating it to a sunnier spot or pruning nearby trees or shrubs that might be blocking the sunlight. Keep in mind that wisteria can tolerate partial shade, but it will produce fewer flowers in these conditions.
In conclusion, encouraging your wisteria to flower involves a combination of factors, including patience, proper pruning, soil amendments, balanced watering, and adequate sunlight. By providing the right care, you can enjoy the stunning, fragrant blooms of your wisteria for years to come.
Wisteria Blooms FAQ
Which Wisteria flowers the longest?
The Chinese Wisteria (Wisteria sinensis) tends to have a longer blooming period than the Japanese Wisteria (Wisteria floribunda). Chinese Wisteria can bloom for around three weeks, while Japanese Wisteria typically blooms for about two weeks. However, the exact duration can vary depending on the local climate, the specific cultivar, and the care the plant receives.
Why does my wisteria not have many flowers?
There are several reasons why your wisteria might not have many flowers:
- Age: Wisteria plants have a long juvenile period and can take several years to start flowering. Be patient if your plant is young.
- Pruning: Incorrect or insufficient pruning can affect the flowering of wisteria. Regular pruning helps stimulate flower bud formation.
- Soil nutrients: Too much nitrogen in the soil can promote leafy growth at the expense of flowers. Ensure that your fertilizer is low in nitrogen and high in phosphorus and potassium.
- Sunlight: Wisteria requires a lot of sunlight to flower properly. Make sure your plant gets at least six hours of direct sunlight daily.
- Watering: Both overwatering and underwatering can stress the plant and affect flowering. Water your wisteria regularly but allow the soil to dry out between watering sessions.
Is tomato feed good for wisteria?
Tomato feed can be beneficial for wisteria as it is typically high in potassium, which promotes flower and fruit development. However, it’s essential to ensure that your wisteria is not getting too much nitrogen, as this can encourage leafy growth and reduce flowering. If you choose to use tomato feed, use it in moderation and in combination with a balanced fertilizer or one specifically formulated for flowering plants.
Which is better, Japanese or Chinese wisteria?
Both Japanese and Chinese wisteria are beautiful and can make excellent additions to your garden, but they have some differences:
- Flower size and shape: Chinese wisteria has larger individual flowers, while Japanese wisteria has longer flower clusters.
- Flowering time: Chinese wisteria tends to bloom earlier in the spring and has a slightly longer blooming period.
- Growth habit: Chinese wisteria twines clockwise, while Japanese wisteria twines counter-clockwise.
Ultimately, the choice between Japanese and Chinese wisteria comes down to personal preference and the specific requirements of your garden. Both species have their unique characteristics, and your decision should be based on your aesthetic preferences and the local growing conditions.
Gareth is the owner of Plantsman Media. Gareth lives in the North East of England and is obsessed with flowers. He has just started RHS level 2 certification.