My aunt said to skip the charcoal layer in my closed terrarium, but my moss turned brown after 2 weeks.

She argued it traps gases and causes rot, but I followed a popular guide that said it's essential for drainage. Has anyone else had a plant fail without charcoal?

3 comments

3 Comments

ninasanchez3mo ago

My cousin's closed jar fern did the same thing, just sort of gave up and got mushy. We used that little gravel they sell for aquariums at the bottom instead of charcoal, and it just pooled water. The whole thing smelled like a swamp when we opened it.

derek_dixon783mo ago

Yeah that swamp smell is the worst. Did you try mixing the gravel with some bigger chunks of bark to keep air pockets?

sagesingh1mo ago

@ninasanchez that swamp smell happens when there's no airflow in the soil layers. The real problem isn't just missing charcoal, it's that the gravel alone can't filter the water right. Moss browns fast when the roots sit in stagnant water without any way to break down the gases. Charcoal actually helps keep things fresh, but even with it you need the gravel layer thick enough to let air move through. Your cousin's fern probably had the same issue, too much water pooling in the bottom with nowhere to go.