Propagating Salvinia oblongifolia (Long Leaf Salvinia)

A practical guide to multiplying Salvinia oblongifolia, an elongated-leaf floating fern, by dividing its branching floating stems into daughter fragments and thinning the surface mat.

Overview

Salvinia oblongifolia belongs to the genus of free-floating aquatic ferns in the family Salviniaceae. Like its relatives it bears its leaves in three-part whorls — two floating green leaves and one finely dissected, root-like submerged leaf — and has no true roots. Hairlike trichomes on the floating leaves keep the surface water-repellent. Its leaves are noticeably elongated, giving an unusual textured surface mat.

It tolerates lower light than many salvinias, which makes it a good surface cover for low-tech tanks. Given enough light and nutrition it still grows quickly and shades the water below.

Propagation Method

Propagation is vegetative, by fragmentation and division of the branching floating stems. As the stems bud and branch, separated pieces grow on as independent daughter plants. Cuttings, spores and sporocarps are not needed for the home aquarium — simply divide the mat.

Step-by-Step

1. Pick a dense, healthy section of the floating mat with firm elongated leaves.
2. Separate the branching floating stems into smaller daughter pieces by gentle pulling; each piece with several leaves will continue to grow.
3. Lift the fragments out with a cup or net so the water-repellent leaves stay dry-side up.
4. Float the daughter pieces on the surface of the new tank, leaves uppermost.
5. Keep surface current weak at first so the light fragments are not pushed underwater or against the glass.

Conditions for Healthy Growth

• Lighting: low light is tolerated; more light increases growth speed.
• CO2: not required.
• Temperature: roughly 20–28 °C is comfortable.
• Nutrients: fed from the water column; pale, light-coloured leaves indicate a micronutrient shortage.
• Flow: calm water with minimal surface current is best.

Maintenance

Thin the mat on a regular schedule so it never seals the whole surface; this keeps light reaching the bottom and maintains gas exchange. Use the removed long-leaf clumps as propagation stock for other tanks.

Common Challenges

• Pale leaves: a micronutrient deficiency; add a complete liquid fertiliser.
• Leaves wetting and sinking: strong surface flow or splashing breaks the hydrophobic hair layer — calm the surface.
• Over-coverage: even a low-light salvinia can spread fast, so trim before it shades out bottom plants.