Iris japonica prefers consistent moisture, especially during its active growth and flowering periods. Water thoroughly when the top 2-3 cm of soil feels dry to the touch.

Reduce watering in cooler months when the plant is less active, but avoid letting the soil dry out completely. Ensure good drainage to prevent waterlogging.

Prune after flowering to remove spent flower stalks and any yellowed or dead foliage. This helps maintain a tidy appearance and directs the plant's energy into producing new growth and future blooms.

In colder climates, you may prune back dead foliage in late winter before new growth appears.

Iris japonica is most easily propagated by division. Carefully dig up the rhizomes in late summer or early autumn after flowering. Separate healthy portions, ensuring each piece has at least one eye or growing point.

Replant immediately in well-draining soil, or pot them for later planting.

Repotting is generally needed every 2-3 years, or when the plant becomes root-bound. The best time to repot is in late summer or early autumn, after flowering has finished.

Use a well-draining potting mix and a pot that is only slightly larger than the current one to avoid overwatering.