Unlike most wisterias that only bloom in the spring, the Blue Moon Wisteria has large and fragrant blue blooms that bloom in spring and twice more over the summer. Blue Moon produces a sweet fragrance that will attract butterflies and create elegant beauty in your yard.
Blue Moon Wisteria
Blue Moon Wisteria or Wisteria macrostachya is a deciduous shrub that can reach heights of 25 feet and a width of up to 8 feet at full maturity. Blue Moon is a hardy cultivar of native wisteria, and it is cold hardy down to -40ºf.
Blue Moon requires minimal care; it requires compost and mulching once a year to maintain soil moisture levels. If the rain is below an inch per week, it will require watering. You should also prune your Blue Moon each winter to encourage new blooms and growth to expect a lifespan of up to 30 years.
The Trunk and Branches
Blue Moon Wisteria is a multi stemmed woody vine that has a twining, trailing growth. The trunk and branches have a texture that can blend into your landscape, but it can be easily balanced with finer or coarser shrubs or trees.
The trunk and branches have a light brown color that allows the beautiful foliage to be showcased.
The Blue Moon Wisteria features beautiful blue flowers that can add amazing color to your garden. The plant first blooms in spring, producing lavender blue flowers that are clustered together. There can be hundreds of flower clusters on the hanging branches to contrast beautifully to the dark green foliage that can grow up to 12 inches in length.
Uses in Your Garden
Blue Moon Wisteria can be quite aggressive, overwhelming any nearby or neighboring plants. It is also well known for growing onto and possibly into any nearby structures. Blue Moon does require a sturdy structure to climb, such as a pergola or trellis. Mature plants can become heavy, so you will need to plan your structure carefully with materials with little risk of breaking.
Blue Moon can be used to brighten up walls or structures that can detract from your landscaping to create an attractive feature. However, due to its invasive nature, it is not recommended that you plant Blue Moon too close to your home.
Blue Moon can thrive in any soil type in climate zones four through nine.
While Blue Moon can grow in partial light, it requires full sunlight to achieve complete bloom. The flowers can tolerate even bright sunshine, but you need to ensure that it has sufficient water during hotter spells, particularly if there has been no rainfall. Blue Moon does have a reputation for being difficult to bloom, but this is often due to a lack of light.
Blue Moon can thrive in all types of soil, but it is a good idea to supplement the soil nutrients with feed in spring. If you have sandy soils that can be vulnerable to low potassium levels, you should also apply a sulphate of potage mixture at ½ an ounce per square yard.
If your Blue Moon is planted in a container, it will need a phosphate based fertilizer or controlled release products to supplement the soil nutrients.
It is also a good idea to add compost to the soil once a year. The compost should be placed in a layer under the plant. In spring, you should also add a couple of inches of mulch over the top of the soil to help control weeds and retain the soil moisture levels.
Blue Moon Wisteria is considered a hardy plant, but they can quickly dry out on sandy or light soils, so you will need to keep your Blue Moon well watered, particularly if they are newly planted or during dry periods.
It is a good idea to monitor rainfall, by planting a cup next to your Blue Moon. If there is less than an inch of water each week, your plant will require additional watering. Water until the soil feels completely moist to ensure adequate hydration for your plant.
Blue Moon Wisteria is considered very winter hardy and can tolerate temperatures as low as -40ºf, when well established. If your Blue Moon is newly planted, you will need to do a little preparation to ensure that it survives the winter conditions.
Water your plant frequently in fall to ensure the soil remains moist rather than wet. Young leaves on wisteria plants can be vulnerable to desiccation in freezing temperatures, so water generously when low temperatures are forecast. You will also need to insulate the roots over winter, by spreading a layer of organic mulch approximately three or four inches thick around the base of the plant. Allow a couple of inches around the vine to be free of mulch, but cover an area of approximately two feet in diameter to insulate the entire root ball.
According to the American Horticultural Society, Blue Moon Wisteria has a heat resistance rating up to zone 9. This rating is based on the average number of days of exposure above 86ºf per year.
Pests and Diseases
There are a few possible diseases and pests that can affect wisteria species, including Blue Moon. These include:
Japanese Beetles: These leaf feeders can destroy the appearance of a wisteria in a matter of weeks.
Scale: Scale insects draw sap from the wisteria, robbing the plant of its essential nutrients.
Mealybug: These bugs produce a residue on the leaves resembling white cotton. This is the egg sacs or pests themselves appearing mostly on the leaves and stems. Besides the residues, mealybugs suck the life out of the wisteria. While one bug may not cause damage, they can quickly multiply and overwhelm the plant.
Aphids: Aphids eat sap, and large infestations can cause significant growth distortions.
Dieback: This condition occurs when the wisteria begins to die from the roots backward due to disease or unfavorable environment.
Crown Gall: This is a common plant disease that is caused by bacterium in the soil and occurs on woody shrubs.
Leaf Miners: These are a species of insects, including sawflies and moths, where the larvae lives in and eats the plant leaf tissues.
Blue Moon Wisteria can also be vulnerable to viral or fungal diseases. This can be shown as irregular brown marks and blotches on the leaves that have a yellow margin or powdery mildew.
In most cases, your Blue Moon wisteria will not require additional fertilisation. It is a good idea to add compost every spring and top with a layer of mulch such as pine needles or finely chopped bark. Using fertilizer products may result in a lush growth, but this can be at the expense of blooms.
As we touched on above, if you have sandy soil, you may need to supplement the nutrient content of the soil with sulphate of pottage. You will also need to ensure that the soil is well irrigated to avoid root problems.
Pruning and Trimming
Blue Moon wisteria has a reputation for pruning difficulties, but this is not the case. Once you’ve established a routine of pruning twice a year, you should enjoy a fantastic display of blooms.
Pruning involves shortening the excess growth in August to about a foot. This will allow the wood to ripen and improve the potential for buds to form. In winter, you should shorten the shoots to up to three buds or approximately four inches to tidy the wisteria before the start of the growing season.
You should leave young wisteria unpruned until they cover the garden structure or wall. You can then begin regular pruning, as this will encourage flowering.
Trimming and pruning can train your wisteria as a free standing container or border plant, or you can train it to grow up into small tree canopies, but this can cause tree damage over time.
The Origins of Blue Moon Wisteria
Blue Moon is one of the species in the American wisteria family. Unlike the Asian wisteria varieties that are considered invasive, American wisteria is native to northern America. Blue Moon is commonly called Kentucky wisteria, and it is native to south central U.S from north Texas and Louisiana to Kentucky, Oklahoma, and Missouri. The name honors Caspar Wistar, a University of Pennsylvania professor of anatomy. While the flowers are considered toxic to both humans and animals, the delightful blue flowers can make a stunning addition to any yard.