When to plant Japanese astilbe?

Astilbe japonica thrives in partial to full shade, making it ideal for borders under trees, woodland gardens, or the shadier corners of your plot where many flowering perennials struggle. It tolerates some morning sun but avoid hot, exposed positions, which will scorch the foliage and stress the plant. Plant in March, April or May for spring establishment, or in September and October for autumn planting; both windows work well provided you keep the soil moist. Soil preparation is critical. Astilbe demands moisture-retentive ground, so dig in plenty of organic matter—well-rotted compost, leaf mould, or manure—especially if your soil is light or free-draining. It performs best in loam, clay, or peat-based soils that hold water without becoming waterlogged. Space plants 35 cm apart to allow for their mature spread of 30–45 cm and to encourage good air circulation. Plant so the crown (where shoots meet roots) sits just below the soil surface, typically 3–5 cm deep. Astilbe roots are fleshy and should not dry out during planting; if bare-root, soak them for an hour beforehand. Firm the soil gently around the roots to eliminate air pockets, then water thoroughly. Apply a 5 cm layer of mulch—bark chips, compost, or leaf mould—around the base to conserve moisture and suppress weeds, keeping it clear of the crown itself. Water again if the weather is dry; establishment depends on consistent moisture in the first growing season.