Propagating Acrostichum aureum (Golden Leather / Mangrove Fern)

How to propagate the large brackish mangrove fern Acrostichum aureum by rhizome division and spores. An emergent marginal plant, not a submerged aquarium fern.

Overview

Acrostichum aureum, the golden leather or mangrove fern, is a robust fern whose glossy, leathery pinnate fronds reach about 1.8 m and occasionally 4 m in ideal conditions. The pinnae are dark green and widely spaced; on fertile fronds the upper five to eight pairs bear brick-red sporangia with a felted look. It inhabits mangrove swamps, salt marshes and river banks.

Propagation Method

Two routes work: rhizome division and spores. Division splits an established clump into rooted rhizome sections for fast, true-to-type plants. Spores from the brick-red fertile pinnae can be sown, but spore germination performs better in fresh water than in brackish conditions.

Step-by-Step

Lift or expose an established clump, keeping the rhizome and roots wet.
Cut the rhizome into sections, each with roots and at least one frond or growing point.
Replant divisions into constantly wet substrate such as garden soil or potting mix.
For spores, collect fertile pinnae bearing brick-red sporangia and sow onto damp substrate in fresh water.
Grow young ferns on in high light and only then acclimatise them to brackish conditions.

Conditions for Healthy Growth

Give it a constantly wet substrate and high light; it grows well in full sun or even deep shade. Fresh water is adequate for cultivation, while in nature it tolerates brackish, saline swamp conditions. It is fast-growing and regenerates easily, vigorous in disturbed mangrove ground.

Maintenance

Remove old or damaged fronds to keep the clump healthy and make room for new growth. Given its size, divide crowded rhizomes periodically to manage spread and produce new plants. Because it regenerates readily, recovery after trimming or division is usually quick.

Common Challenges

Poor spore germination if sown in brackish rather than fresh water.
Substrate drying out, when this fern needs constantly wet ground.
Underestimating its size; fronds can reach 1.8 m or more and need space.
Trying to grow it submerged, when it is an emergent marginal species.