Maintain consistently moist soil, especially during the growing season. Sium ninsi thrives in waterlogged or marshy conditions. Water regularly to prevent the soil from drying out, simulating its natural wetland habitat.

Reduce watering slightly in cooler months but never allow the soil to become completely dry.

Pruning is typically minimal and primarily involves removing dead or damaged foliage to maintain a tidy appearance. Trim back any overgrown stems to control spread or to encourage bushier growth.

This can be done at any time of year as needed.

Propagation is best achieved through division of established clumps in early spring. Carefully separate the root ball, ensuring each division has healthy roots and shoots.

Alternatively, seeds can be sown in moist soil in autumn or early spring, though division is generally more reliable.

Repot Sium ninsi every 2-3 years, or when it outgrows its container. This is best done in early spring before new growth begins. Use a well-draining, yet moisture-retentive potting mix.

Ensure the new pot is only slightly larger than the current one to avoid overwatering issues.