Astilbe ‘Spinell’ is a vibrant perennial that brings striking color and texture to garden spaces, particularly in shady areas. This plant is a popular choice for gardeners seeking to add consistent visual interest and a touch of elegance to their landscapes. Its adaptability makes it a favored specimen for various garden designs, from borders to woodland settings.
Understanding Astilbe ‘Spinell’
Astilbe ‘Spinell’ is a clump-forming perennial, typically reaching 20-36 inches (50-91 cm) tall with a 12-18 inch (30-45 cm) spread. Its foliage emerges bronze-red in spring, maturing to lush, deep green with finely serrated leaves. The most striking feature is its vibrant crimson-red flower plumes, rising above the foliage from June to August. These feathery plumes add an airy texture and attract pollinators like bees and butterflies. In autumn, the green foliage can develop subtle red hints, extending its seasonal appeal.
Growing Conditions for Astilbe ‘Spinell’
‘Spinell’ prefers partial to full shade, especially in hotter climates, to protect its foliage from intense afternoon sun. While it tolerates full shade, blooming may be reduced. In cooler climates, it can handle more sun if consistently moist.
It performs best in rich, well-draining soil that remains consistently moist. Ideal soil pH for ‘Spinell’ ranges from slightly acidic to neutral, between 5.5 and 6.5. Amending the soil with compost or organic matter significantly improves fertility and moisture retention.
Consistent moisture is crucial; ‘Spinell’ does not tolerate drought. Deep, regular watering is recommended, particularly during the growing season and hot spells, ensuring the soil stays moist but not waterlogged. Applying mulch helps retain soil moisture and keeps roots cool. ‘Spinell’ is hardy in USDA zones 4 through 8, indicating its tolerance to a range of temperate climates.
Ongoing Care and Maintenance
Ongoing care maintains the health and vigor of ‘Spinell’. Fertilization supports robust growth and abundant blooms; a balanced, slow-release fertilizer or compost applied in early spring is sufficient. A phosphorus-rich formula (e.g., 5-10-5 or 10-10-10 NPK) can promote flowering. An additional application of compost or organic fertilizer can be given mid-season.
Pruning is minimal. Deadheading spent flower plumes encourages a tidier appearance, though faded plumes often remain attractive through autumn and winter. Cut back foliage to ground level in late fall or early spring for new growth. Divide mature clumps every three to four years to maintain vigor and prevent overcrowding. This is best done in late winter or early spring by separating the root ball into sections.
For winter care, established Astilbe ‘Spinell’ plants are generally hardy and can survive cold temperatures without extensive protection. In colder climates, apply a 2-inch layer of mulch around the plant in late fall to insulate roots and retain soil moisture. Ensure adequate moisture until the ground freezes.
Common Challenges and Solutions
Astilbe ‘Spinell’ can encounter a few common issues. Leaf scorch, characterized by browning leaf margins, results from excessive direct sun or insufficient moisture. Ensure adequate shade, especially from afternoon sun, and consistent deep watering to prevent this.
While resistant to most pests, ‘Spinell’ may be affected by spider mites in hot, dry conditions. Signs include stippled leaves and fine webbing. Increasing humidity and rinsing foliage can manage mites.
Diseases like powdery mildew and leaf spot can occur, especially in humid conditions or with poor air circulation. Proper spacing and watering at the base of the plant reduce the risk of these fungal issues.
A lack of blooms might indicate insufficient light or nutrient deficiencies. While ‘Spinell’ prefers shade, too much deep shade can reduce flowering. Adjusting planting location to receive dappled sunlight or providing a balanced fertilizer encourages more prolific blooming. Some fungal wilts are untreatable, requiring removal of affected plants to prevent spread.