Get Wisteria to Bloom

Wisterias in bloom are a beautiful sight to behold. The lavender flowers cascade beautifully down the sides of buildings, pergolas, bushes, which makes wisteria the envy of many gardeners. This robust vine can scale buildings with multiple stories and is strong enough to bring down structures that are supporting it, if they are not sturdy enough. However, it can be a struggle to get the flowers to bloom. If you provide the ideal environment, add phosphorus to the soil, and do the necessary pruning, it will be possible to get your own wisteria plant to bloom.

Steps

Pruning Wisteria

  1. Prune in February and July. Winter pruning for wisteria is best done in February on a mild day. Then, pruning in the summer will cut back on the unruly growth and keep the plant in check. It is important to restrict the vegetative growth so that the flowering spurs are encouraged to blossom.[1]
    • Pruning in the winter is generally easier because the leaves have been shed and the framework of the plant is exposed.
  2. Prune the long shoots. The shoots are the new branches that have grown since the summer. They should be cut back so that there are only three to five buds per shoot. This will generally mean that three to four inches will be cut off each one.
    • Pruning the branches will direct the plant’s energy to flowering. [2]
  3. Avoid cutting the plant frame. While the shoots can be cut back, the main woody frame of the plant should not be cut. Maintaining a strong frame will ensure that the integrity of the plant remains intact.
  4. Cut the new growth back six inches. This creates better air circulation and allows the sunlight to reach the new growth. This improves the chances of the formation of flower buds.[3]
  5. Completely remove unnecessary shoots from the main framework. For older plants, it is necessary to remove branches that are run-down and branches that have grown over structural features of buildings, such as windows and doors.
    • This is known as a “hard prune” and it will stimulate strong growth, as this is a plant that can grow aggressively. To avoid this, avoid fertilizing in the first spring after the hard prune.[3]
  6. Leave the seedpods. Many gardeners find the seedpods of the wisteria plant to look decorative. You can leave the seedpods if you enjoy how the look; otherwise, it is acceptable to remove them.

Adding Phosphorus to the Soil

  1. Purchase a phosphate fertilizer. Using a fertilizer will encourage your wisteria to blossom. You can find phosphate fertilizer from an online retailer, or you can find it in a local or a big box store.
  2. Add the phosphate fertilizer to the soil. You should only do this in the early spring, such as April. When you have the fertilizer in your possession, read the instructions on the package and heed any warnings.
    • If you have plenty of time to fertilize, use a natural fertilizer and apply it to the surface of the soil. This method takes a longer time to release nutrients into the soil.
    • If you are short on time to fertilize, use a water soluble fertilizer. This is a fluid solution that is dissolved in water and is sprayed onto the soil and the plants.
    • Many times, when struggling to get a wisteria to bloom, too much nitrogen is the culprit. Adding phosphorus to the soil will balance the nitrogen already present in the soil and will encourage the wisteria to blossom.
  3. Add compost to the soil. Each spring, you should add compost to the soil around the wisteria. Apply a two-inch covering of mulch on top of the compost. This will retain moisture and deter weeds from growing around the plant.

Creating the Ideal Environment

  1. Plant wisteria in its ideal climate, if possible. Wisteria is best suited for the United States Department of Agriculture’s Hardiness Zones 5 through 9.[5] Although it can grow and adapt to just about any environment in the United States and other countries that do not have extreme climates, it will grow best in Zone 5, located along the United States’ Midwest and Central regions.[6]
    • The USDA Plant Hardiness Zone Map is the standard used by gardeners to determine which plans are likely to thrive in certain locations.
    • Zones 5-9 cover most of the continental United States, with the exception of upper midwest region, which covers, Minnesota, North and South Dakota, Montana, northern Michigan, and the northern portion of Wyoming.
  2. Ensure that wisteria gets plenty of sunlight. The various types of wisteria need a different amounts of sunlight to bloom. Generally speaking, wisteria grows best with sunlight all day long.
    • Either check online by performing an internet search or check at a gardening store to find out how much sunlight is appropriate for the plant that you would like to bloom.
    • Chinese wisteria can bloom in partial shade.
    • Japanese wisteria requires full sunlight to bloom.
  3. Protect wisteria from frost. Newly planted wisteria does not do well in cold weather and the buds can be damaged by frost in the spring. If you live in an area with cold weather, you will need to plant wisteria somewhere that is sheltered so that the buds are protected from the frost.[7]
    • You can shelter the plant by wrapping it in burlap during the winter and when frost is expected during the spring. Be sure to keep an eye on the weather and stay on top of any frost warnings.
    • You can also plant wisteria so that it is protected by a structure, such as a screen, but this may not work if the species of wisteria requires a lot of sun.
  4. Give wisteria extra water between July and September. This is when the buds for next year are formed and the plant could benefit from some extra water.[7]
    • Wisteria does not need to be watered often and should actually only be watered if you live in an area that receives less than an inch of rain per week. Otherwise, wisteria will receive enough water.[4]

Tips

  • Plan to give an established wisteria plant a major pruning every three years or so to retain its shape.
  • Wisteria need full sun and moist, well-drained soil to blossom. They also prefer a sheltered location such as against the brick wall of house to protect them from the harsh winter winds.
  • When left untended, wisteria can grow into a tangle of branches in a single season, encroaching upon nearby plants and putting excess pressure on its trellis or other support structure. Prune the plant heavily to the desired size and shape, thinning overcrowded stems. New shoots will begin to grow quickly. Select the most vigorous of the new growth and begin training them to grow along wires, a trellis or up a tree.
  • Train wisteria to grow vertically by making cuts on downward-facing buds while pruning.

Warnings

  • Do not use high-nitrogen fertilizer around wisterias, including lawn fertilizers, because the nitrogen will encourage leafy growth rather than flower blooms.

Things You'll Need

  • Mature wisteria that has bloomed in the past
  • Pruning shears
  • Pruning saw
  • Pail
  • Shovel
  • Twine

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Sources and Citations

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