Propagating Egeria densa (Anacharis)

How to propagate the fast-growing oxygenator Egeria densa from stem cuttings, plus a serious warning about its invasive spread when released into the wild.

Overview

Egeria densa, sold as Anacharis or Brazilian waterweed, is one of the easiest aquarium plants to multiply. Its trailing stems can reach two metres or more and produce roots at intervals along their length, so a single plant readily becomes many. It also functions as a useful oxygenator in the aquarium.

Cultivated plants are a single male clone that reproduces only vegetatively, which is why every new plant you raise comes from a cutting rather than from seed.

Propagation Method

Propagation is by stem cuttings and fragmentation. Because the species roots at nodes along the stem, almost any healthy section will form roots and continue growing. This same high dispersal capacity from fragments is exactly what makes the plant dangerous outside the aquarium.

Step-by-Step

Select a healthy stem and cut a section 10–15 cm long, ideally with several leaf whorls.
Strip the leaves from the lowest node so the bare node can sit in the substrate.
Push the bare node about 2–3 cm into the substrate, or simply let the cutting float to root freely.
Within days roots emerge from the buried or submerged nodes and the cutting grows on independently.

Conditions for Healthy Growth

Egeria densa thrives across a very wide range. It grows well in low light, matching its photosynthesis to whatever light is available, and tolerates temperatures from roughly 16 to 28 °C, slowing only above about 32 °C. It can grow in water up to 4 m deep but reaches the surface and then spreads horizontally.

Trimming & Maintenance

Trim regularly to keep the fast-growing stems from forming a dense surface canopy that blocks light to lower plants. Top cuttings can be replanted, and the trimmed lower stem will continue to grow, giving you a steady supply of new plants.

Common Challenges

The main challenge is its own vigour: left untrimmed it forms a thick mat at the surface that shades everything beneath it. Sudden leaf drop usually follows a large change in light or temperature.