When to plant Red valerian?

Centranthus ruber, commonly known as red valerian or spoorbloem, thrives in full sun or partial shade and is remarkably unfussy about soil. It performs best in well-drained sandy, loamy, or chalky soils and actually prefers lean, alkaline conditions—avoid rich, heavy ground that stays wet. The plant is ideal for dry banks, gravel gardens, walls, and coastal sites where many other perennials struggle. Plant spoorbloem in March, April, or May for establishment before summer, or in September and October to give roots time to settle before winter. Space plants 45 cm apart to allow for their mature spread of 40–60 cm. Dig a hole slightly larger than the root ball, loosen the soil at the base, and position the crown at the same level it sat in the pot. Backfill with excavated soil—there's no need to add compost or manure, as spoorbloem dislikes overly fertile conditions which encourage floppy growth at the expense of flowers. Water in thoroughly after planting to settle roots, then water sparingly. Once established, Centranthus is drought-tolerant and needs little supplementary watering except during prolonged dry spells in the first season. Mulching is generally unnecessary and can retain too much moisture around the crown. If planting in autumn, avoid waterlogged sites over winter. Spoorbloem often self-seeds freely in cracks and crevices, so if you want a more naturalistic effect, allow a few seedheads to mature after the first flush of flowers.