Sweetly fragrant, the wisteria vine is one of the most aromatic garden plants. It’s fragrance coupled with the plant’s lavender or violet blue flowers also makes it one of the most distinctive garden plants. If you can keep their vigorous growth habit under control the plants are also pleasingly easy to grow.
This is your complete guide to growing and caring for the wisteria vine.
Aromatic and attractive, the flowers of the wisteria vine are a great way to bring height and structure to a space. If trained correctly the plants can also bring privacy to an open garden.
Warning All parts of the wisteria vine is toxic to pets and humans. The plants contain both lectin and wisterin. These can cause nausea or sickness. If consumed in large quantities they can also be deadly.
These toxins are particularly concentrated in the seeds and seed pods of the plant. Deadheading the flowers prevents seeds from forming.
Interestingly if you do allow the seed pods to form and remain on the plant they eventually ripen and explode. This explosion makes a loud popping noise that can startle unsuspecting people and animals.
This habit of exploding seed pods is designed to spread the seeds as far from the parent plant as possible. This allows new plants to grow without the danger of overcrowding.
Choosing the Right Variety
If you go to a garden store or nursery you will find a range of wisteria vine plants for sale. Take the time to research the growth habits and preferences of each cultivar. Selecting the most suitable plant for your growing situation helps you to grow a healthy, flower filled plant.
Chinese and Japanese wisteria are not native to North America. In some states and regions the plants are considered invasive.
Native wisteria vine plants are not considered invasive. Native plants are also more suited to your growing conditions. This means that they can be easier to care for and are often less susceptible to common pests and diseases.
The native varieties of wisteria vine are:
- American wisteria (W. Frutescens)
- Kentucky Wisteria (W. Macrostachya)
American wisteria is suitable for gardeners in USDA zones 5 to 9. Native to many states, including Texas, Iowa, Michigan and Virginia it can reach a height of 30 ft. Producing glossy dark green foliage and large lilac flowers with a light fragrance it is a reliable cultivar.
Kentucky wisteria grows in USDA zones 4 to 9. Native to the south east of the US, it flowers relatively late in the season, producing fragrant blue-purple flowers within a few years of planting.
Blue Moon is an extra-hardy cultivar of Kentucky wisteria. Producing silver-blue flower clusters in late spring and early summer, it is hardy to minus 40 ℉.
Both native varieties of vine set flowers on new wood. This eliminates the dangers of frost damage. Just be careful when pruning not to remove too much new wood. This can hamper flowering.
Native varieties set bloom on new wood. Over pruning a plant, and removing all the new wood, can lead to a failure to flower.
Where to Position Your Wisteria Vine
Your chosen position should be sunny. Full sun positions are ideal. While wisteria vine grows in partial shade but may not flower. The plants require at least 6 hours of sunlight every day to flower. Wisteria vine dislikes the cold, so the warmer the position the better.
The plants prefer rich soil that is evenly moist. Working the soil over before planting and amending with organic matter, such as well rotted manure or compost, helps to enrich the soil.
Digging over the soil also improves drainage. Wisteria vine does better in well draining positions.
Once planted these vine are pleasingly drought tolerant. In fact the only regular care the plants need is pruning.
Supporting Your Wisteria Vine
These are sprawling, twining plants. They require support in order to promote and control its growth habit.
Growing the vine up a trellis or along an arbor is ideal. While many people grow wisteria vine on the wall of a building, planting in an open area is better. This enables you to access all areas of the plant.
Make sure that your chosen support is secured firmly in the ground. As plants grow they can become surprisingly heavy, placing a lot of pressure on the support structure. If the structure isn’t solid enough, or firmly secured, it can break or fail.
A metal structure, such as this Metal Pergola Arbor, provides a firmer support than a wooden trellis. Setting the support in concrete also helps to create a firm structure.
Don’t allow wisteria to vine around a tree. While this may look attractive it can eventually strangle the tree.
Select your support structure carefully. As it grows the plant can become heavy, moving or breaking weak supports.
How to Plant
Plant either in the spring or fall, when the plant is dormant.
Don’t plant too closely to other plants. The quick growth habit of wisteria vine means that it can quickly smother other, smaller plants.
To plant, use a shovel to dig a large hole in the prepared soil. The hole should be deep enough to hold the root ball. It should also be twice as wide as the plant’s root system. To check the size of your hole, place the plant, in its container, in the hole. If the hole is big enough the pot will comfortably fit.
Carefully remove the plant from the pot. If the plant is difficult to remove, try squeezing the sides of the pot. This loosens the soil, helping you to remove the plant.
Position the plant in the hole, the root system should sit just below the soil level. Fill in the hole and firm down the soil. Water well.
If you are planting more than one, space the plants 10 to 15 ft apart.
Growing in Containers
You can also grow wisteria vine in a pot. This is a great way to control the plant’s growth habit. In particular single stem plants are ideally suited to container planting. They are also easier to train than multi stem plants.
Begin by planting in a pot only slightly larger than the one currently holding the plant. Gradually increase the size of the pot as the plant grows.
The pot should be clean and have drainage holes in the bottom. Placing a layer of pebbles or crocks on the bottom of the pot further helps to improve drainage. Fill the container with fresh, general purpose potting soil. Plant as you would in the ground.
Planting is also the best time to install a stake or some form of support for the plant to grow along. As the plant grows continue to train or tie it to the support.
When the stem reaches the top of the support cut off the tip. This stunts the upward growth habit of the plant. Instead it begins to bush out, becoming more rounded.
Care for a wisteria vine in a pot is similar to in the ground.
Water regularly so that the soil doesn’t dry out and fertilize in the spring to promote healthy growth. Prune the plants every winter, don’t allow the shoots to exceed 1 ft in length.
How to Transplant
While sometimes necessary, transplanting a large wisteria vine is difficult. It can also lead to the vine failing to flower for a number of years. You should only transplant if absolutely necessary.
The larger the plant grows the more difficult transplanting can be. A difficult process, even if successful, transplanting can cause the plant to cease flowering for a few years, until it is fully settled in its new home.
The best time to transplant a wisteria vine is when the plant is dormant, either in late fall or early spring. Transplant in early morning or in the evening.
Before you transplant, cut the vine down so that it is no more than 3 ft tall.
Use a shovel to dig about a deep circle about 24 inches in diameter around the central stem. Dig deeply, aiming to get as much root as possible. The more root and soil you can lift and transplant the more likely the plant is to survive.
In the new position dig a large hole, roughly twice the size of the root ball. Mix soil from the hole with compost or leaf mold. Aim for an even mix, this enriches the soil, helping your vine to establish itself.
Position the plant in the hole and firm the soil down. Water well.
How to Train and Prune a Wisteria Vine
Some varieties such as American and Kentucky wisteria send out vines that twine counterclockwise. Others, such as Japanese wisteria set vines in a clockwise direction. Working with the growth habit of the plant makes training a lot easier than if you try to go completely against the plant’s natural habit.
Begin by attaching upright stems to your chosen support structure. As the vine grows upwards, remove any side shoots that emerge. If you need to fill in side spaces allow one or two side branches to remain, attaching them to the support where required.
Aim to space side branches roughly 18 inches apart. This enables air to circulate through the plant, keeping it healthy.
Once the plant reaches the optimum height pinch out, or cut away, the main vine tip. This stunts the upward growth habit of the plant.
How to Prune
Continue to control the growth of the plant by pruning away new shoots throughout the growing season. Regularly pruning the shoots helps to keep the plant at a manageable size.
In the fall, once growth has ended for the year, prune heavily with garden scissors or pruning shears. Aim to remove about half of the year’s growth, leaving a few buds on each stem.
Don’t worry about over pruning. Wisteria vine has a vigorous growth habit. The more harshly you cut it back, the stronger the plant returns next year.
As you prune remove any dead wood and crowded branches. Cut back side branches so that they spread no more than 1 ft from the main trunk.
Remove any suckers that are emerging at the base of the plant.
For a more formal appearance you can also prune in the summer, around two months after flowering ends. Alternatively if you want to encourage flowering cut the shoots back every two weeks during the summer months.
If your wisteria is particularly overgrown it can be pruned down to about 3 ft below its desired height. While the plant will grow back, a drastic pruning like this can prevent flowering for a few years, until the new shoots mature.
Don’t worry if after pruning, larger branches seem to die away. This is perfectly natural. Simply cut them away from the plant.
How to Care for Wisteria Vine
Once planted wisteria vine is pleasingly easy to care for. Mulching with a layer of compost every spring helps to suppress weed growth. It also helps the soil to retain moisture.
When to Water and Fertilize
Unlike other plants that require regular watering, the wisteria vine prefers to be slightly underfed and underwatered. Too much of either can discourage flowering and cause excess leaf production.
Apply a few cups of bone meal each spring and a similar dose of rock phosphate in the fall. This helps to promote healthy growth. An application of phosphorus encourages flowering.
Once established don’t overwater or fertilize your wisteria. A little stress encourages the plants to flower more profusely. Too much fertilizer or water can encourage leaf production at the expense of flowering.
How to Propagate
Propagating wisteria is pleasingly easy. While the plants can be propagated from seed, this is a slow process. It can take up to 15 years for plants grown from seed to flower.
Instead propagate either via cuttings or by layering. Either method can take up to 4 years to produce a flowering plant. Whichever method you choose, propagation is best done during the summer.
Layering a Vine
To layer, select a healthy, flexible stem. Bend it down to the ground so that a leaf node is contacting the soil.
Bury the node and part of the stem in the soil. You may need to place a pebble on the stem to hold it in position.
By the following spring the node will have produced its own root system. The stem can now be cut from the main plant and repotted on its own.
How to Take Cuttings
Cuttings are best taken in late spring or early summer from softwood. This is green growth that has not yet developed a woody bark.
The cutting should be 3 to 6 inches long. It should also have at least two sets of leaves.
Remove any flower buds. Cut away the leaves from the lower half of the cutting. Trim the stem down so that the lowest leaf node is about half an inch from the bottom of the cutting.
Dip the cutting in rooting hormone and plant in a pot filled with moist, well draining potting soil. Cover in a plastic wrap or bag. This helps to maintain humidity levels. Don’t allow the sides of the plastic to touch the cutting. Bamboo canes can be placed in the soil to form a protective frame around the cutting.
Place the cutting in a bright, indirect light position. Water when the soil is dry to the touch. Roots should develop in 6 weeks. To check roots are forming, gently pull the cutting. If you feel resistance from the plant it means that roots are forming.
After roots have developed, plant on the cutting into a larger pot or its final position.
Forming at the base of the plant suckers, or offshoots, can be potted on and grown as new plants.
The best time to remove the suckers is in early spring or late winter. To remove an offshoot, insert a shovel between the sucker and mother plant. Force the shovel down, severing the root that binds the sucker and plant.
Carefully lift out the sucker and its rootball. Remove any weeds or dirt from the roots.
Plant the suckers in light positions in holes that are 2 ft wide and deep. Water the soil well before planting and work in organic matter such as well-rotted compost.
Suckers should be planted to roughly the same depth as when they were attached to the mother plant. If you are unsure, plant so that the top of the root ball is just below the soil level.
Gently firm the soil down, eliminating air pockets, and water well. Keep the soil evenly moist for about a year after planting.
Like other forms of propagation, transplanting suckers can be a slow process. The plants like to be fully settled in a position before they begin to produce flower buds.
If your plant is failing to bloom don’t worry. These vining plants are often slow to flower. It can take up to 3 years after planting for plants to flower. However, once established, if properly cared for, the plants flower profusely.
Fungal diseases are common problems, particularly in warm areas. Properly spacing the plants and watering the soil not the foliage can help to prevent problems. A fungicide can also be applied at the beginning of the growing season to protect plants.
How to Cure Leaf Curl
Leaf curl is usually caused by either a lack of fertilizer or pests sucking the sap from the foliage. Aphids and scale can both cause leaf curl.
If your plants are pest free try conducting a soil test. A soil test kit is easy to acquire and use. It provides you with valuable information such as the chemical makeup of your soil.
Poor soil, or soil lacking in nutrients, can prevent flowering or cause leaf curl. To amend poor soil, apply a balanced fertilizer. Be careful not to overfeed. Too much nitrogen in the soil can cause leaf production at the expense of flowering.
Is Yellowing Foliage Natural?
Yellowing leaves are often the product of cold weather during the fall or winter months. This is natural. Yellowing leaves at other times of the year may be the sign of poor drainage.
Planting in wet or soggy soil can cause plants to yellow before becoming limp and falling from the plant. It can also be a sign of iron deficiency or an overly alkaline soil. A soil pH test tells you the condition of your soil, helping you to amend these problems.
Tobacco mosaic virus is a common pest. Leaving foliage mottled and streaked, adopting good growing practices helps healthy plants to survive attacks from this pest.
Regularly check your wisteria vine for signs of disease or infestation, such as wisteria borer. Catching problems early gives you the best chance of curing them and saving your plant.
Buds failing to open can be a sign of thrips. While the flowers won’t open for this season, the plant should be okay and flowering the next year.
Wisteria borer can enable diseases to enter your plants. These are most problematic in young plants. Adopting good growing practices and keeping plants healthy helps to prevent attacks.
If your plant does fall prey to wisteria borer a chemical control can be used. Alternatively you can simply pick the pests from the foliage and crush them between your fingers.
Fragrant, colorful and easy to care for the wisteria vine is a reliable addition to any garden.
Fragrant and colorful, wisteria vine can live a long time if cared for correctly. In fact one of the oldest known examples, found in Ashikaga Flower Park in Japan, can be dated back to 1870.
While they may be slow to establish themselves, once they are happy the wisteria vine is a reliable and vigorous grower, filling your garden with fragrance and color.