Propagating Caulerpa peltata (Disk Caulerpa)

How to propagate Caulerpa peltata, a marine green macroalga, by dividing its creeping stolon runner, with warnings about going sexual and the invasiveness of the Caulerpa genus.

Overview

Caulerpa peltata is a marine green macroalga of the genus Caulerpa, recognised by its disc-shaped (peltate) fronds. Like all Caulerpa it is coenocytic — the whole alga is effectively a single cell with many nuclei, making it one of the largest single cells in nature.

It grows as a creeping runner, or stolon, that spreads across the substrate anchored by rhizoids, sending upright fronds (assimilators) toward the light. In marine refugiums it is valued as a fast nitrate absorber that helps export nutrients from the system.

Propagation Method

Caulerpa propagates vegetatively by rhizoid extension and fragmentation. To multiply it you divide the stolon (runner): each separated piece carrying fronds and rhizoids will re-anchor and continue growing. This is runner division, not the substrate cuttings used for stem plants.

Step-by-Step

1. Choose a healthy section of stolon bearing several fronds and rhizoids.
2. Pinch or cut the runner to separate that section from the parent mat.
3. Lay the piece on rock or rubble in the new refugium so the rhizoids can re-anchor.
4. Keep lighting and flow steady and let the fragment re-establish before harvesting again.

Conditions for Healthy Growth

As a tropical marine macroalga it wants stable reef-tank conditions: full-strength salinity, alkaline pH around 8.0–8.4 and warm temperatures. Provide medium lighting on a refugium photoperiod and steady water flow.

• Stable salinity and alkaline marine pH.
• Medium lighting, often run opposite the display tank's cycle.
• Some dissolved nutrients to fuel the rapid growth that drives nutrient export.

Maintenance

Harvest regularly — pulling out roughly half every couple of weeks keeps it actively growing and absorbing phosphate, and is the most effective way to prevent it from going sexual. Never let an unpruned mass build up.

Common Challenges

Beyond going sexual, the genus is a known invasive: Caulerpa taxifolia escaped the aquarium trade and overran parts of the Mediterranean, Australia and southern California. Because of these risks many reefers now prefer Chaetomorpha, which exports nutrients without the same hazards. Never release Caulerpa into the wild.