Water Pepper thrives in consistently moist to wet conditions. Keep the soil saturated, especially during warmer months. In containers, ensure the pot is sitting in a tray of water.

Reduce watering slightly in cooler periods but never allow the soil to dry out completely, as this species prefers boggy environments.

Pruning is generally not required for Water Pepper unless it becomes overgrown or leggy. If desired, trim back stems in late spring or early summer to encourage bushier growth.

Remove any dead or damaged foliage at any time of year to maintain the plant's health and appearance.

Water Pepper is easily propagated by stem cuttings or by seed. Cuttings can be taken in spring or summer and rooted in water or moist soil. Seeds can be sown directly in moist soil or water in spring.

It also readily self-seeds in suitable conditions, often spreading enthusiastically.

Repotting is rarely necessary for Water Pepper, as it is often grown in marginal bog gardens or ponds.

If container-grown and it outgrows its pot or becomes waterlogged, repot in early spring into a larger container or directly into a suitable aquatic environment. Use a heavy loam-based compost.