Caulerpa prolifera Propagation: Dividing the Stolon Runner

How to propagate flat-blade Caulerpa prolifera in a marine refugium by dividing its creeping stolon runner, with care, nutrient-export and going-sexual crash notes.

Overview

Caulerpa prolifera is a green marine macroalga whose body is built from single, strap-like blades joined by underground stolons (creeping runners) that are anchored to sandy substrate by rhizoids. Remarkably, each plant is a giant single cell with multiple nuclei. It grows in shallow Mediterranean, eastern Atlantic and warm American coastal waters, where it helps consolidate the seabed. In the aquarium it is kept mainly in refugiums and FOWLR systems as a fast nutrient-exporting macroalga.

The plant shows strong plasticity: in bright light it stays compact, highly branched and dense, while in shade the blades grow longer and thinner. Because it is propagated vegetatively rather than from substrate cuttings, the key to multiplying it is dividing the runner, not planting blade fragments in sand.

Propagation Method

Caulerpa propagates by fragmentation of the stolon (the horizontal runner). New plants regenerate from very small pieces of tissue, only a few millimetres across, so dividing a healthy runner that already carries blades and rhizoids is the reliable approach. There is no need for rooting hormones, special media, or cutting individual blades into the sand.

Select a vigorous, fully green section of stolon bearing several blades.
Divide it into segments, each keeping at least one blade and some rhizoids.
Anchor the segments so the rhizoids contact the substrate or rock.

Step-by-Step

Choose a clump where the stolon is firm and deep green, with no pale, hollow or translucent areas.
With clean scissors, cut the stolon between blade nodes into segments a few centimetres long, each holding a blade and rhizoids.
Place each segment on or just into the sand, or wedge it against live rock so the rhizoids can grip.
Keep flow gentle for the first days so cuttings are not swept loose before they attach.
Watch for new blade tips emerging from the stolon over the following days to confirm establishment.

Conditions for Healthy Growth

Provide stable reef-typical saltwater: roughly 22-28 °C, pH about 8.0-8.4, and moderate lighting. As a fast grower it draws down nitrate and phosphate, which is why refugium keepers value it. Sediment-rich sand suits it because the rhizoids take up nutrients directly from the substrate, an advantage over macroalgae that feed only from the water column.

Maintenance

Harvest regularly, removing whole blades and surplus runner so the mass stays open and healthy; this is how nutrients are physically exported from the system. Avoid letting it become a dense, light-starved mat. Discard trimmings in the trash, never down a drain or into natural water.