Building your first closed terrarium
Five layers, one jar and an evening. How to build a closed terrarium that waters itself, and how to keep the balance once the lid goes on.
A closed terrarium is a small water cycle. The plants breathe out moisture, it condenses on the glass and runs back into the soil. Get the layers right and it looks after itself.
The five layers
- Drainage: 3 cm of clay pebbles or gravel.
- Barrier: a thin layer of moss or mesh so soil does not wash down.
- Charcoal: a sprinkle to keep things fresh.
- Soil: a peat-free mix, deep enough for the roots.
- Moss and plants: fittonia, small ferns and cushion moss work well.
Finding the balance
Light condensation in the morning is perfect. If the glass stays fogged all day, open the lid for an hour. If it never fogs, add a few sprays of water.
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