Nuphar japonicum

Scientific name: Nuphar japonicum

Family: Nymphaecaceae

Maximum size reached under cultivation: 40 - 60 cm (15.75 - 23.62 inch)

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Recommended pH range: 6.5 - 7.5

Recommended water hardness: 4 - 12°dGH (71.43 - 214.29ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 15 - 25 °C (59 - 77°F)

Preferred propagation method: Rhizome

Native to: East Asia

Growth rate: Slow

Recommended substrate: Fine gravel

Lighting requirements: Bright

Ideal placement in tank: Background

Family

Nymphaeaceae

Common Name

Spatterdock, Japanese Spatterdock

Origin

East Asia – primarily Japan, Korea, and parts of China.

Propagation

This plant reproduces both by seeds and vegetatively through rhizome division. In aquariums or paludariums, the easiest method is dividing the thick rhizome into sections with healthy leaves and roots. Seed propagation is possible if the plant is allowed to flower above the water surface and the flowers are manually pollinated.

Difficulty

Medium

Short Description

Nuphar japonicum is a marsh and marginal plant that can also be grown in aquariums with open tops or in paludariums. It features broad, waxy, heart- or arrow-shaped leaves that float on or emerge above the surface. Under suitable conditions, it produces bright yellow, cup-shaped flowers. While it can adapt to submerged life for short periods, it thrives best with part of the plant exposed to air. Avoid fully burying the rhizome, as it may rot.

Tank Placement

Best used as a background or marginal plant in large aquariums, or as a centerpiece in a paludarium setup. Leave room for floating leaves to spread and ensure bright lighting.

FAQs

• Can Nuphar japonicum be fully submerged?

  Only temporarily. While the plant can adapt for a short time, it grows best when allowed to send leaves to the surface or grown as a marginal/paludarium plant.

• How do I prevent the rhizome from rotting?

  Plant the rhizome partially above the substrate, with the crown exposed. Do not fully bury it, and use nutrient-rich, well-drained substrate.

• What kind of lighting does this plant need?

  Bright lighting is essential for healthy leaf development and potential flowering. It can tolerate medium light but growth will slow significantly.

• Can it flower in an aquarium?

  Yes, if the plant has access to open air and strong lighting. It produces small yellow flowers above the waterline.

• Tips for pond or paludarium growth?

  Provide shallow water (10–30 cm), nutrient-rich substrate, and access to air. This setup mimics its natural environment and supports robust flowering and growth.