The Blue Fountain Bush, scientifically known as Caryopteris x clandonensis, is an ornamental shrub recognized for its vibrant blue flowers, which provide a welcome splash of color in the late growing season. Its mounding, “fountain-like” shape contributes to its visual appeal in various garden settings, making it an attractive feature with unique late-season blooms.
Understanding the Blue Fountain Bush
The Blue Fountain Bush presents a compact, mounding growth habit, typically reaching a mature size of 2 to 3 feet tall and wide. Its most notable characteristic is the profusion of true blue flowers that emerge from late summer through autumn, often continuing until the first frost. These small, fluffy blossoms cluster in whorls along the stems, creating a soft, airy appearance.
The foliage features finely textured leaves that are often silver-green and aromatic when crushed. Some cultivars also display variegated leaves with golden edges, adding visual interest. This deciduous shrub sheds its leaves in late autumn. The plant is also known by common names such as Bluebeard or Blue Mist Shrub.
Ideal Growing Conditions
The Blue Fountain Bush thrives in environments with ample sunlight. Full sun exposure, meaning at least six hours of direct sunlight daily, is recommended for optimal growth and abundant flowering. While it can tolerate partial shade, prolonged periods in lower light conditions may result in less vigorous growth and fewer blooms.
Well-draining soil is a requirement for this plant, as it does not tolerate soggy conditions, which can lead to root rot. A neutral pH, ranging from slightly acidic to slightly alkaline (pH 6 to 8), is suitable. The plant is adaptable to various soil types, including average or sandy soils, performing best in fertile, moist, but well-draining loam. The Blue Fountain Bush is hardy in USDA hardiness zones 5 through 9. When planting multiple bushes, spacing them about two feet apart allows for adequate air circulation.
Planting and Ongoing Care
Planting the Blue Fountain Bush is best done in spring after the last frost, though autumn planting is possible in warmer regions, allowing about a month for root establishment before a heavy freeze. To plant, dig a hole approximately twice as wide as the rootball and deep enough so the plant’s crown rests at the same level as it did in its original pot. After placing the shrub, backfill with soil, gently tamp it down, and water thoroughly to settle the soil around the roots.
During its establishment phase, regular watering encourages a deep root system. Once established, the Blue Fountain Bush exhibits drought tolerance and requires supplemental watering only during prolonged dry spells. For container-grown plants, more frequent watering is necessary when the top 2 inches of soil feel dry. Fertilization is minimal; a balanced, slow-release fertilizer applied in spring is sufficient, as excessive nitrogen can promote foliage growth at the expense of flowers.
Pruning is important for the Blue Fountain Bush, as it flowers on new wood. The best time for pruning is in late winter or early spring before new growth begins. Cut back stems to about 6 to 8 inches from the ground or to strong buds on the woody frame. This hard pruning encourages robust new growth and a profusion of blooms. Deadheading spent flowers after blooming encourages continuous flowering and maintains a tidy appearance.
Troubleshooting and Common Problems
A lack of blooms on the Blue Fountain Bush often stems from insufficient sunlight, as the plant requires ample direct light to produce flowers. Improper pruning, such as pruning too late in the season after new growth has started, can also reduce flowering, since blooms appear on new wood. Ensuring the plant receives full sun and is pruned correctly in early spring helps address this.
Leggy growth, characterized by long, sparse stems, frequently results from inadequate sunlight or a lack of proper pruning. Regular hard pruning in early spring helps maintain a compact, mounding shape and promotes denser foliage. Over-fertilization, especially with nitrogen-heavy fertilizers, can also lead to excessive leafy growth at the expense of flowers, contributing to a leggy appearance.
The Blue Fountain Bush is generally resistant to most pests and diseases. However, root rot can become a problem if the plant is situated in poorly drained or overly saturated soil. Ensuring well-draining soil and avoiding overwatering are important preventative measures. While less common, issues like spider mites or aphids might occasionally appear, and fungal diseases such as powdery mildew could develop in humid conditions, though these are typically not severe.