Fringed willowherb prefers consistently moist soil. Water deeply when the top inch of soil feels dry, especially during warm, dry periods. Avoid waterlogged conditions, as this can lead to root rot.

Reduce watering frequency in cooler months or when the plant is dormant.

Prune back dead or spent flower stalks in late autumn or early spring to maintain a tidy appearance and prevent self-seeding. Remove any dead or damaged foliage as needed throughout the growing season.

This encourages new growth and can improve plant vigor.

Fringed willowherb is easily propagated by seed sown in autumn or early spring. Division of established clumps in early spring is also an effective method.

The plant readily self-seeds, so collecting seeds from mature plants is straightforward.

Repotting is generally not necessary unless the plant is severely pot-bound or its growth is significantly diminished. If repotting is required, do so in early spring before new growth emerges.

Use a well-draining potting mix and a slightly larger container.