Astilbes

Astilbes are herbaceous perennial plants in the genus Astilbe, family Saxifragaceae. Native to Asia, they form clumps of fernlike, pinnate leaves and produce tall, plume-like flower stalks. The flower clusters are made up of numerous small blossoms and come in colors such as white, pink, rose, and red. Size varies by cultivar, typically ranging from about 0.3 to 1.2 meters in height.

Culture and habitat

Astilbes prefer moist, well-drained soil rich in organic matter and thrive in partial to full shade. Some cultivars tolerate morning sun if kept consistently moist, but hot, dry conditions can reduce vigor. Mulching helps conserve moisture in summer. They are hardy in USDA zones 4 through 9, with tolerance depending on the specific cultivar. Good drainage and regular moisture are important to prevent stress and decline.

Care and propagation

Plant crowns at or slightly above soil level, spacing plants about 18 to 24 inches apart. Fertilize lightly in spring and avoid heavy topdressing that can promote foliage at the expense of flowering. Division of clumps every 3 to 4 years helps maintain vigor and provides material for new plantings. While seeds can be propagated, most garden stock is grown from divisions or established cultivars.

Pests, diseases, and uses

Astilbes are relatively pest-resistant but can be affected by powdery mildew in humid conditions, and slugs or snails may cause localized damage. They are widely used in shade and woodland gardens, borders, and near water features. The flowers attract bees and other pollinators, contributing to garden biodiversity.

Notable cultivars and species

Common cultivated hybrids include Astilbe x arendsii, derived from Astilbe chinensis and Astilbe japonica. Species such as Astilbe chinensis and Astilbe japonica provide additional color and form variations.