Many of the most beautiful small melastomes, such as Bertolonia and Sonerila, are forest-floor herbs that suffer in ordinary living rooms. Dry air and strong light damage them quickly. A terrarium recreates the conditions they evolved in.
Open or closed?
- Closed terrarium: a lidded container holds humidity very high. It suits the most demanding species but needs ventilation to avoid mould.
- Semi-closed: a lid that is left slightly ajar, or a cabinet with a small opening. A good compromise for most growers.
- Open terrarium: easier to maintain, but humidity is lower, which suits tougher species.
Choosing a container
Use glass or clear plastic with good visibility. Wide containers give more surface area and are easier to plant. Check that you can reach into it for maintenance.
Building the layers
- Drainage layer: a few centimetres of clay pebbles or coarse gravel, so excess water has somewhere to go.
- Barrier: a thin layer of mesh or sphagnum to keep substrate from washing into the drainage layer.
- Substrate: a loose, airy, slightly acidic mix such as coco coir, sphagnum, fine bark and perlite.
- Surface: a layer of live or sheet moss for looks and to help hold moisture.
Avoid garden soil, which compacts and can bring in pests and disease.
Light
Strong sun in a glass box overheats the interior. Provide bright shade, or use a grow light of moderate intensity for around twelve hours a day. If leaves bleach or scorch, reduce the intensity or move the light further away.
Temperature and humidity
Aim for mild, stable temperatures. Humidity in a semi-closed terrarium commonly stays high, which these plants like. For details on watering practices, see watering and humidity for melastomes.
Watering
Water sparingly with low-mineral water such as rainwater or distilled water. The substrate should be damp, not waterlogged. Condensation on the glass is normal. If water pools at the bottom, remove some and reduce watering.
Companions
Plants with similar needs include small ferns, mosses, fittonia, and some begonias and peperomias. Choose slow-growing species so that nothing smothers your melastomes.
Troubleshooting
- Mould or fungus: increase ventilation, remove affected material and avoid overwatering.
- Fungus gnats: let the surface dry slightly between waterings, and use a layer of sand or fine grit on top.
- Rot: usually from overwatering or poor drainage. Remove affected parts.
- Leggy growth: light is too low. Increase intensity gradually.
- Brown tips: air that is too dry or minerals in the water.
Propagation
Soft stem cuttings of creeping melastome herbs often root easily in a humid environment. Take a short piece with a few leaves, place it on damp substrate or in water, and keep it humid.
Sourcing plants responsibly
Small forest-floor melastomes are vulnerable in the wild. Buy only from reputable growers who propagate their own stock, and avoid any plant sold as wild-collected. See conservation of melastomes for background.
Takeaways
- A semi-closed terrarium suits most small melastome herbs.
- Use an airy, acidic, moisture-retentive substrate.
- Give gentle light and use low-mineral water.
- Ventilate to prevent mould.