Emma Sibley, right, of London Terrariums advises on growing plants under glass indoors
Terrariums were invented by a Victorian entomologist Nathaniel Bagshaw Ward. He discovered miniature ferns growing in a sealed jam jar intended for a moth chrysalis and realised that it provided the ideal environment for tropical plants. They protected the plants from dust and pollution, maintained a high humidity, and regulated the temperature, so plants could photosynthesise, be self-sufficient and water themselves.
Any clear vessel is suitable
for a terrarium. It shouldn’t be air tight, though, eg, remove rubbers seals from Kilner jars. Open terrariums need to be watered and misted to stop plants drying out.
The secret to keeping plants alive
in a terrarium is not to water. Terrariums are self-sustaining: plants produce heat and oxygen which condenses on the glass which is enough to keep them alive. They will need sunlight to photosynthesise but not direct light. You may need to take the cork out occasionally to dry the plants a bit and decrease humidity but this will be rare.
The best plants to put in a terrarium
are those from tropical, humid and damp climates. Ferns, miniature palms, Ficus pumila and Fittonia, which is native to the jungles of Peru, all work well.