Phlox paniculata 'Sternhimmel'

This herbaceous perennial forms upright, vigorous, and bushy clumps. It typically reaches a height of 80 - 100 cm (31-39 inches) and spreads about 40 - 50 cm (16-20 inches) wide. It's a robust and relatively stable variety.

Deciduous, the leaves are broadly lance-shaped and a fresh medium green, providing dense foliage along the stems.

The most distinctive feature of 'Sternhimmel' is its unique flowers. They are relatively large and appear in dense, conical panicles. Each petal is distinctly star-shaped with pointed tips, featuring a white base that transitions to a delicate bluish-purple, culminating in a striking deep violet-blue eye. This intricate coloring creates a mesmerizing, shimmering effect. The flowers release a pleasant, sweet fragrance and bloom profusely from July to September, attracting a variety of pollinators.

Thrives in full sun to light partial shade. A sunny location encourages the most abundant blooms and vibrant colors. Crucially, ensure good air circulation around the plants to minimize the risk of powdery mildew. Avoid overly sheltered, warm, and humid spots.

Excellent frost hardiness (down to below -28°C / -18°F, USDA Zones 4-8). It reliably overwinters outdoors.

Prefers fresh to moist, nutrient-rich, and well-drained garden soils. The soil should be rich in humus and should never completely dry out. Good drainage is essential, as waterlogging, especially in winter, can lead to root rot.

Ideal for perennial borders, cottage gardens, cutting gardens, and as an elegant group planting. Its unique bloom shape and color make it an excellent focal point or a complementary plant that adds intricate detail to any summer display.

Medium to high water requirement. The soil should be kept consistently moist throughout the growing season, particularly during dry spells and the blooming period. Applying a layer of mulch can help retain soil moisture effectively.

Relatively low maintenance. Regular deadheading of spent flower clusters promotes a longer and more abundant rebloom and prevents unwanted self-seeding. In late autumn or early spring before new growth emerges, the plant can be cut back to the ground. To prevent powdery mildew, besides ensuring good ventilation, water directly at the base of the plant, avoiding overhead watering. Dividing clumps every few years in spring can help maintain the plant's vigor and flowering performance.

Containerized plants can be planted year-round, as long as the ground is not frozen. The optimal planting times, however, are spring (March to May) or autumn (September to November) to allow the plant the best establishment.