Japanese Clethra prefers consistent moisture, especially when young or during dry periods. Water deeply when the top 2-3 cm of soil feels dry. Avoid waterlogged conditions, as this can lead to root rot.

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

Prune to shape and remove dead or damaged branches. The best time for major pruning is in late winter or early spring before new growth begins.

Lightly deadhead spent flowers to encourage a tidier appearance, though this is not essential for the plant's health or flowering next season.

Japanese Clethra can be propagated from softwood cuttings taken in early summer. Dip the cuttings in rooting hormone and plant them in a well-draining, moist potting mix.

Alternatively, seeds can be sown in autumn, but germination can be slow and erratic. Layering is another successful method.

Young plants may need repotting every 1-2 years, typically in early spring before active growth starts. Choose a pot only slightly larger than the current one. Use a well-draining, peat-based potting mix.

Mature plants generally prefer to be root-bound and may not require frequent repotting.