Water marsh elder regularly during its establishment period, ensuring the soil remains consistently moist. Once established, it tolerates drier conditions and prefers well-drained soil.

Avoid waterlogging, especially in winter. Reduce watering in cooler months, allowing the soil to dry out slightly between waterings.

Prune marsh elder in late winter or early spring before new growth begins. Remove any dead, damaged, or crossing branches.

To maintain a tidy shape and encourage dense flowering, cut back flowering stems by about one-third to one-half their length. This also prevents the plant from becoming leggy.

Marsh elder is readily propagated by stem cuttings taken in late spring or early summer. Select healthy, non-flowering shoots, cut them into 10-15 cm lengths, and remove lower leaves.

Dip the cut ends in rooting hormone and insert them into moist, well-drained potting mix. Keep in a warm, bright location.

Repot marsh elder only when it becomes root-bound, typically every 2-3 years. Do this in early spring before new growth emerges.

Choose a pot that is slightly larger than the current one and use a well-draining potting mix. Water thoroughly after repotting and place in its usual growing conditions.