How To Grow And Care For Wisteria

After the spring blooms fade, keep the ambitious wisteria vine trained and maintained.

Fact checked by Emily Peterson

Wisteria is one of the first harbingers of spring and warmer weather. Encouraged by the daffodils, which have already braved the cold weather and opened their faces to the sun, clusters of purple and pink wisteria blooms can be seen suspended on vines, trailing in and out of the still barren tree branches and along fence lines. In a matter of days, the entire wisteria vine will be a riot of bright green leaves and fragrant, opulent flowers. Just like gardenias and azaleas, wisteria is an essential member of the Southern garden. But unlike the aforementioned plants, wisteria wears out its welcome rather quickly. The beautiful and fragrant blooms fade quickly and you are left with an ambitious, aggressive vine that can quickly consume trees, arbors, and porches. The gorgeous, show-stopping wisteria can become an invasive nuisance when it is neglected and untrained, so here are some tips on choosing the right variety for your use and how to keep it from overwhelming your property. Interestingly, wisteria leaves and flowers are edible, though the raw seeds are toxic to humans. The plant is toxic to pets.

Wisteria Care

Ready to plant a new wisteria vine? Cut the bottom from a large plastic tree container, dig a hole big enough for the container and place it in the ground, then plant your wisteria directly in it. The container walls will help control lateral root growth. Wisteria is not fussy about soil but needs good drainage, and it generally doesn't need fertilizer. Most of the maintenance of these climbers comes from training and pruning them.

The sight of colorful wisteria weeping gracefully down and across a porch is an iconic picture of a Southern garden, but the reality is far different than the romance. This beautiful image requires some hard-core maintenance to keep the vines from overtaking your gutters and drain spouts. Be careful about which type of wisteria you plant, which we discuss below.

Light

Wisteria blooms best in full sun. You'll want to site it away from buildings and trees, unless you want it to scramble up them in search of more light. American wisteria (Wisteria frutescens) and Chinese wisteria (W. sinensis) can also grow in partial sun, or two to six hours of direct sun a day, but may produce fewer blooms.

Soil

In general, if you have moist, well-drained, slightly acidic soil, wisteria will do fine. Japanese wisteria (W. floribunda) will grow in nearly any soil, whether wet or dry and clay, loam, or sand. This aggressive plant can form thickets just about anywhere in full sun, but does prefer acidic soil with a pH of 6.0. The less aggressive American wisteria thrives in moist soils, especially well-drained, fertile, and slightly acidic clay or loam.

Water

Wisteria is fairly drought-tolerant once established. Keep the soil moist in the first growing season, watering when dry. In subsequent years, your wisteria will appreciate a good soaking when the weather is hot and dry.

Temperature And Humidity

American wisteria can grow in Zones 5-9, which covers all but the Tropical South. Japanese wisteria is more cold hardy and also grows in Zone 4. Chinese wisteria is said to do best in Zones 5-8, but has been found growing in warmer areas like Florida. These plants like humidity but can also grow in a dry climate with adequate watering.

Fertilizer

Wisteria should grow just fine without fertilizer, especially if it's planted in the ground. Container-grown plants may require fertilizing. If you're looking to boost your blooms, choose a high-phosphorus fertilizer and apply just once in spring. Wisteria is a nitrogen-fixing plant, and applying too much nitrogen fertilizer will reduce blooming.

Types Of Wisteria

Two of the more popular species of wisteria, Japanese wisteria and Chinese wisteria, both feature overhanging vines with clusters of fragrant blue, purple, pink, or white pea-shaped flowers in early spring. They grow fast, and if not controlled by regular pruning, quickly consume whatever is in their path. Sounds a lot like kudzu. In fact, the plants can't be sold in Maryland without signage declaring them invasive, and Chinese wisteria is banned in Delaware. Many states recommend against planting Japanese and Chinese wisteria.

Instead of spending the season running around your yard with a pair of clippers, you may want to try 'Amethyst Falls,' a form of our American native wisteria. This is a strong grower, reaching 30 feet or more, but is not invasive like its Asian cousins and is ideally suited for growing in containers, training up a trellis, or even growing as a small free-standing tree. 'Amethyst Falls' will bloom in its first season, and the blooms arrive about two weeks later than blooms from the Asian wisteria, so late-winter frosts seldom affect flowering. Need more reasons to love this wisteria? It is deer-resistant and drought-tolerant.

Another type of wisteria once considered an American subspecies has since been classified as a separate species called Kentucky wisteria (W. macrostachya). 'Blue Moon' is a popular cultivar in cooler climates as it is hardy to Zone 4. 'Blue Moon' does not grow quite as vigorously, growing to 15-25 feet, and can bloom as many as three times a year in late spring and summer.

Pruning

Wisteria should be pruned every year to keep the plant manageable. Asian wisteria flowers on one-year-old growth, while 'Amethyst Falls' blooms on new wood, so keep that in mind as you shape your vine.

After the plant has bloomed, remove any new growth you don't want to keep. For Asian wisterias, prune new shoots that you retain back to about 6 inches long, retaining some buds so that those branches can flower in the second year. Saving some of those shoots will result in a better flower show. If your vine grows out of control over the summer and fall, you can prune it again in winter. Cut any suckers back to ground level when they pop up in your yard.

'Amethyst Falls' can be pruned more aggressively in winter, as it will develop flower buds on new growth in spring. 'Blue Moon' can be pruned in winter, but heavy pruning may cause the plant to vine heavily at the expense of flowers. Because 'Blue Moon' can bloom a second or third time, prune lightly in summer to retain as many flower buds as possible.

Wisteria vines produce long seed pods that look much like a pea. If you are growing an invasive wisteria, it's best to remove and dispose of them before they mature.

How To Train Wisteria to Frame a Porch

To safely train wisteria along the top of a porch, heed this advice from the Grumpy Gardner: Run a metal pole from one porch post to another about 18 inches below the crossbeam. Let the vine's branches and runners twine only around the pole. Once flowering finishes, you'll need to prune the vine regularly if you want to maintain clear sightlines from your porch.

How To Train a Wisteria Tree

You can purchase an already-trained wisteria tree, or you can train your own. Here is how: Remove all but one main stem and stake this one securely. Using plastic tape, tie the stem to the stake at intervals. When the plant has reached the height at which you wish the head to form, pinch or prune out the tip to force branching. Shorten the branches to beef them up, pinch back long streamers, and rub off all buds that form below the head.

Wisteria Needs Good Support

The twining, woody vines of wisteria will overpower flimsy wooden arbors, so choose one with a sturdy metal frame. Let the vine climb a corner post to the top, and tie it to the arbor. Train it so most of its branches and runners lie atop the arbor and wrap around themselves rather than the posts and rafters.

Propagating Wisteria

Wisteria can be propagated from softwood cuttings. This method is much preferred to starting plants from seed, as new seedlings can take as long as 15 or 20 years to mature and bloom. To propagate your wisteria, you'll want to use soft, green growth from the current year, preferably towards the top of the plant:

1. Cut the tip of a stem about 3-6 inches long. Remove the leaves from the lower half of the cutting.

2. Stick the bottom of the cutting in a pot filled with moist, sterile mix made of 1/2 peat and 1/2 perlite or 1/2 peat and 1/2 sand. Make sure that at least 1/3 of the stem is buried.

3. Water well and cover the stem and pot with clear plastic. Place in bright, indirect light and keep moist.

4. Once the cutting has developed a good root system, you can repot it in good potting soil. Growing the plant to a larger size in a pot and gradually acclimating it to garden conditions will increase the chances of your new vine surviving.
   

Potting And Repotting Wisteria

Wisteria can be grown in a pot, but this is most suitable for vines trained into tree form (also called a standard). The better-behaved native wisterias are a good choice for containers. Wisteria is a heavy plant, and you may only want to pot it once. Choose a sturdy pot that is 18 inches or wider in diameter. Use well-drained soil and stake the plant as discussed above. Water regularly during the first growing season, and provide 1 inch of water a week in subsequent years (more water may be beneficial during hot, dry spells). Fertilize once each spring with a low-nitrogen, bloom-boosting fertilizer.

Common Pests & Plant Diseases

Wisteria plants have few serious problems. Japanese beetles, aphids, leaf miners, scale insects, and mealybugs can be attracted to the plant. If infestation becomes a problem, spraying insects with a strong stream of water, picking them off and putting dropping them in a can of soapy water, or using insecticidal soap may help.

In the case of leaf spots, simply pick off and dispose of affected leaves. Powdery mildew can coat the leaves with a grayish-white mold, but usually doesn't cause a problem. You can spray leaves with fungicide if the plant's health is affected.

Wisteria sometimes develops crown gall, a lump of gnarled wood on the stem. Crown gall is essentially a tumor caused by bacteria and cannot be treated. An established plant may survive for years with crown gall, but a newer plant should be pulled up and disposed of in the trash. If you prune a wisteria with crown gall, you'll need to sterilize your pruners afterward with a 10-percent solution of household bleach.

Honey fungus can attack wisteria from the soil. Symptoms include cracking at the base of the stem, white fungal growth at the base, and gradual dying of upper branches. Sometimes honey-colored mushrooms will appear at the base. Unfortunately, honey fungus can't be stopped once infection occurs.

How To Get Wisteria To Bloom

A lack of blooms is the most common problem home gardeners have with wisteria. If spring has passed you by without any sign of lovely lavender flowers, consider the following:

• New transplants usually take two or three years to settle into your garden before they start blooming.

• A late frost may have zapped the flower buds in spring.

• Too much nitrogen fertilizer will prevent the plants from blooming. Stick to bloom-boosting fertilizers that are high in phosphorus.

• Wisteria do not bloom in full shade and even partial shade, depending on the species. Increase light exposure if needed.

• Pruning practices can make a difference. Pruning is best done right after flowering and should be done every year. Japanese wisteria blooms best when new shoots are cut back to three or four buds.

If all else fails and another bloom-free year passes you by, you can try root pruning your plant in fall to encourage it to bloom the following spring. Take a sharp spade or shovel and cut straight down through the roots around your plant. Make a circle about 2 feet from the main stem.

For more Southern Living news, make sure to sign up for our newsletter!

Read the original article on Southern Living.