Great moss for tropical terraria use due to its texture and density. – Fern moss (Thuidium Delicatulum) grows quite large and dense, which creates a lush carpet. Fern moss prefers high humidity and low to medium light. It will do great in any of our Bio Bottles when other plants provide some shade for it. Plant on a substrate that retains moisture but ensure the moss does not get submerged, it does not tolerate getting waterlogged.