Growing Wisteria

Few plants can rival the dramatic spring beauty of a wisteria vine in full bloom. Despite the showy flowers and delightful scent, wisteria plants have acquired a reputation for being difficult to grow. Don't be fooled. With the right growing conditions and some occasional pruning, wisteria is a beautiful, fast growing vine - and a worthwhile addition to nearly any garden.

Plant Characteristics

Popular for their long, hanging clusters of violet flowers, there are around a dozen wisteria species available to gardeners, including two native to North America. The most common types grown are the Asian species Japanese wisteria (W. floribunda), and Chinese wisteria (W. sinensis).

Japanese wisteria tends to have more vibrant color blooms and Chinese wisteria a sweeter scent. Both species need a large amount of growing space and look very similar in appearance. You can tell the difference between the two by the way they climb. The stems of Japanese wisteria twine around supports in a clockwise direction, while the stems of Chinese wisteria twine in a counterclockwise direction.

The Best Zones for Wisteria

Wisteria grows best in zones 3 to 9. Not all varieties are suited to all zones, however, so check carefully to make sure the wisteria you choose is a proven performer where you live. If you lack space (or the ability to erect a sturdy support structure), the smaller American forms of the vine, such as Kentucky wisteria (W. macrostachya) or American wisteria (W. frutescens) don't grow as quickly and can be good substitutes for smaller gardens.

Where to Grow Wisteria

Wisteria will grow in partial shade and marginal soils but performs best in sunny locations (6 or more hours per day) and in moist, fertile soils that drain well. Wisteria needs a large amount of growing space. These plants are vigorous climbers (growing 10 feet or more annually) and are easily capable of climbing to heights of 25 feet.

Once established, the Asian species can become invasive and difficult to get rid of - especially in the east. To help restrain the plant's spreading root system, wisteria can be planted in large containers buried in the ground.

Planting Wisteria

1. To plant wisteria, work the soil deeply (18 to 24 inches) around the hole where the vine will be planted.
2. Mix a couple handfuls of compost or well-rotted manure in with the original soil.
   Advertisement

   
   
3. Set the plant on the ground at the same height it was growing in the pot.
4. Water in well and add a layer of organic mulch around the base of the plant.
5. Keep your newly planted wisteria watered well for several weeks after planting to allow it to become established.

Pruning Wisteria

Wisteria needs to be pruned a minimum of twice yearly to keep plants tidy and promote flowering.

• 1st-Summer Pruning (just after flowering): Cut off the tips of all of the side shoots as well as the tips of any new growth. Also, remove any suckers that appear at the base of the plant.
• 2nd-Late Winter Pruning: Cut the main stems back by about half. You may also shorten side shoots slightly; cut them back to only a couple of inches from where you see the flowering spurs (little pegs).

Training Wisteria

You never have to worry about over-building supports for wisteria. Mature vines are heavy and will require ample support. To train young plants to grow on a trellis or arbor, choose an upright stem to serve as the leader and secure this to the support. You can then remove some of the side shoots and train the remaining shoots to grow horizontally across the supports, or simply let them all twine across the supports naturally. Pinch off the main leader when it reaches the desired height.

Five Reasons Wisteria Fail to Bloom

One of the more frustrating aspects of growing wisteria is waiting for them to reach maturity and then watching them fail to bloom. Here are five common reasons wisteria fail to produce flowers:

1. Immature plants. Depending on whether you are starting new plants from seeds, cuttings, or young nursery stock, it can take 5, 10, or even 15 years or more before wisteria start to produce flowers. Start with grafted plants or those grown from cuttings that are known to have flowered relatively young. These plants usually flower much sooner than those grown from seed.

Advertisement


2. Too much nitrogen (or insufficient phosphorus). Some gardeners make the mistake of over-fertilizing wisteria to encourage them to flower. This can actually work against them, because excess nitrogen encourages the plant to produce foliage, usually at the expense of flowers.

3. Planting too deeply. Setting plants in the ground too deeply may result in a delay of flowering or prevent them from blooming altogether.

4. A lack of sun. Too much shade can cause vines to flower poorly. Although some types of wisteria may be root-hardy to Zone 4, many varieties won't bloom reliably there. In Zone 5, plants may sometimes fail to bloom after a severe winter freeze kills off flower buds.
5. You're being too kind. Pruning is key to getting wisteria to flower. You have to keep pruning all of those errant new vines that keep sprouting up. Depending on the soil the species you're growing, and environmental conditions, you may need to snip shoots as often as every 4 to 6 weeks.

Growing Wisteria from Seed

Wisteria plants are often started from layered cuttings, but they are also easy to grow from seed.

1. When the seedpods turn brown in the fall, remove the seeds and allow them to dry.
2. Store them in the refrigerator until spring.
3. In the spring, sow seeds directly in the ground (or in containers) after soaking them in water for 24 hours.
4. It's important to note that wisteria grown from seed may not resemble the parent plant in form or color.
5. They will also take longer to reach flowering size - anywhere from 10 to 15 years.