Cyperus alternifolius Umbrella Sedge

Cyperus alternifolius — the Umbrella Sedge — is one of the most recognisable marginal plants in horticulture, widely grown as a houseplant and water garden feature across the world. It is native to Madagascar and nearby Indian Ocean islands, growing in marshy ground and along watercourse margins where it forms dense, clumping colonies of tall, triangular stems each topped with a radiating whorl of narrow leaf-like bracts resembling the spokes of an umbrella.

In paludariums and open-top aquariums it thrives with its root zone submerged or in waterlogged substrate, sending stems upward into the humid air above. It is a robust, fast-growing plant that tolerates a wide range of conditions including warm tropical temperatures, moderate hardness, and varying light levels. It is also commonly kept as an indoor houseplant with its pot standing in a saucer of water.

Although not a submerged aquarium plant, C. alternifolius is an excellent emergent accent for large open-top displays, paludariums, and outdoor pond marginalia, providing bold architectural vertical structure that contrasts naturally with submerged aquatic planting below the water surface.

Light: High; requires bright light for strong, upright stem growth; weak light produces floppy, pale stems. CO2: Not required; an emergent plant using atmospheric CO2. Fertilisation: Rich, moist substrate or aquatic fertiliser tabs every 8 weeks; liquid feed monthly during active growth. Placement: Marginal zone of paludariums or pond edges; stems grow above water into open air. Propagation: Divide clumps at the base; can also root stem tips placed upside-down in water — an unusual and reliable method.