The ‘Blue Moon’ wisteria is a distinct and popular woody vine, known for its beautiful, fragrant, lavender-blue flowers. This North American native cultivar is celebrated for its vigorous growth, improved cold hardiness, and ability to produce abundant blooms. Its adaptability to various garden structures and reliable performance make it a favored choice for many gardens.
Blue Moon Wisteria Overview
‘Blue Moon’ wisteria (Wisteria macrostachya ‘Blue Moon’) is a deciduous woody vine. It typically reaches a mature height of 15 to 30 feet, with a spread of 4 to 8 feet. Its vigorous growth rate necessitates a sturdy support structure.
The distinctive feature of this wisteria is its fragrant, pea-like, lavender-blue flowers, which appear in cascading racemes 6 to 12 inches long. Unlike some other wisteria varieties, ‘Blue Moon’ is a repeat bloomer, often producing flowers up to three times in a single growing season once established, usually starting in late May or early June. This cultivar is notably cold-hardy, thriving in USDA Hardiness Zones 3 to 9, and can withstand temperatures as low as -30°F to -40°F. Its foliage consists of deep green, odd-pinnate leaves that provide a lush backdrop to the blooms.
Planting Your Wisteria
Selecting the proper site is important for establishing ‘Blue Moon’ wisteria. The plant requires full sun exposure, meaning at least six hours of direct sunlight daily, to ensure optimal flowering. While it can tolerate some partial shade, insufficient sunlight may hinder bloom production. Choose a location protected from strong winds, especially for young plants.
Soil preparation is equally important. ‘Blue Moon’ wisteria thrives in well-draining, moderately fertile, humusy soil that is slightly acidic, with a pH range of 6.0 to 7.0. Before planting, amend the soil with organic matter such as compost or well-rotted manure to improve drainage and provide initial nutrients.
When planting, dig a hole twice as wide as the root ball and just as deep, ensuring the plant sits at the same level as its nursery container. Gently place the wisteria in the center, then backfill with the amended soil, lightly tamping it down to remove air pockets. After planting, water deeply to settle the soil around the roots. Immediately establish a sturdy support structure, such as an arbor, pergola, or strong trellis.
Essential Care Practices
Consistent care practices promote the health and abundant flowering of ‘Blue Moon’ wisteria. Full sun exposure is paramount, encouraging numerous flower buds. While the plant can tolerate some shade, its most spectacular displays occur in locations receiving direct sunlight for the majority of the day.
Watering should be consistent, especially during dry periods and throughout the first few growing seasons to aid establishment. Aim to provide about one inch of water per week, watering deeply at the base of the plant. Avoid overwatering, as overly wet conditions can lead to root issues. Once established, ‘Blue Moon’ wisteria exhibits some drought tolerance, but consistent moisture during active growth periods is still beneficial.
Applying a layer of organic mulch around the root zone helps retain soil moisture, regulate temperature, and suppress weeds. ‘Blue Moon’ wisteria generally requires minimal fertilization. An application of a balanced or phosphorus-rich fertilizer in early spring can promote flowering. Avoid high-nitrogen fertilizers, as excess nitrogen encourages lush foliage growth at the expense of flower production.
Pruning and Training
Proper pruning is essential for maximizing bloom production and managing the vigorous growth of ‘Blue Moon’ wisteria. It encourages the plant to form flowering spurs, maintains its desired shape, and controls its size. Without regular pruning, the vine can become a tangled mass of vegetative growth with fewer flowers. Promptly remove any dead, damaged, or crossing branches throughout the year to maintain plant health and improve air circulation.
Training the vine onto a sturdy support structure should begin immediately after planting. Guide the main structural branches along the arbor, pergola, or trellis, securing them loosely with soft ties if needed. As the vine grows, continue to direct its main stems to cover the support, establishing a strong framework. This early training helps distribute the vine’s weight and ensures it grows in the desired direction.
‘Blue Moon’ wisteria benefits from two main pruning times. Winter pruning occurs in late winter or early spring, while the plant is dormant. Shorten the previous season’s growth to two or three buds to promote flowering spurs and maintain overall structure. Summer pruning, typically performed after the first flush of blooms in July or August, involves cutting back the current year’s long, whippy shoots to five or six leaves. This practice helps control rampant growth, encourages repeat blooming, and channels the plant’s energy into flower development.
Common Challenges
A common challenge when growing ‘Blue Moon’ wisteria is a lack of blooms. Factors contributing to this include insufficient sunlight, over-fertilization with high-nitrogen products, improper pruning techniques, or the plant being too young. ‘Blue Moon’ wisteria may take two to three years to establish and begin blooming.
While generally robust, ‘Blue Moon’ wisteria can be affected by pests. Common insect issues include aphids and scale insects. These can be managed with horticultural oils or insecticidal soaps if infestations are severe. Providing good air circulation around the plant can help deter many pest problems.
Fungal diseases, such as powdery mildew and leaf spot, may occur, particularly in humid conditions with poor air circulation. Powdery mildew appears as a white, powdery coating on leaves, while leaf spot causes dark spots. Ensuring adequate spacing and pruning for good airflow can help prevent these issues. ‘Blue Moon’ still exhibits vigorous growth. Regular and consistent pruning, as detailed in care practices, is the most effective way to manage its size and prevent it from overwhelming its support structure or surrounding areas.