Propagating Nuphar japonica (Japanese Spatterdock)

A practical guide to multiplying Japanese spatterdock by dividing its thick rhizome into sections with growth points, with notes on conditions for its large submerged and floating leaves.

Overview

Nuphar japonica, the Japanese spatterdock, is an aquatic perennial relative of the water lilies that grows from a thick rhizome, typically 1 to 3 centimetres across. It produces submerged, floating or emerged leaves, with blades reaching 12 to 35 centimetres long. Native to Japan, Korea and Russia, where it occurs in lakes, ponds and streams, it is widely grown as an ornamental plant in aquaria and ponds.

Because the plant grows from a rhizome rather than a stem, it is multiplied by rhizome division. It also sets seed, as the fruit bears ovoid seeds, but division is the fast and dependable route in the aquarium.

Propagation Method

The main method is rhizome division: the thick rhizome is cut into sections, each of which must carry at least one growth point so it can throw up new leaves. Seed propagation from the ovoid seeds is possible but slower and mainly relevant in ponds.

Step-by-Step

1. Lift the rhizome and clean off substrate so you can see the growth points and leaf bases.
2. With a clean sharp blade, cut the rhizome into sections, each keeping at least one active growth point.
3. Trim away any soft, rotten or hollow rhizome tissue from the cut sections.
4. Anchor each section in nutrient-rich substrate as a root feeder, leaving growth points exposed.
5. Allow new submerged leaves to establish before the plant pushes floating leaves to the surface.

Conditions for Healthy Growth

Japanese spatterdock is undemanding. It does well in low light and without added CO2, drawing most of its nutrients from the substrate through its rhizome, so a nutrient-rich base layer is important. Give it room, as a single specimen develops large leaves and can dominate a medium to large aquarium.

Maintenance

Remove old or floating leaves periodically so light reaches the lower submerged foliage and the tank does not become shaded. Keep the rhizome firm and inspect it occasionally; trim away any section that turns soft. Divide established rhizomes only when the plant has grown large.

Common Challenges

• Rhizome rot if a section is divided without a healthy growth point.
• Shading of the lower aquarium as floating leaves multiply.
• Slow start when planted in lean substrate without enough root nutrition.
• Oversized leaves crowding smaller plants in compact layouts.