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Terrarium maintenance

Watering a terrarium should be done with care.
Photo: Jardin botanique de Montréal (Gilles Murray)
Masdevallia caudata 'Janet' AM/AOS orchid in a terrarium

Here’s some advice for taking proper care of your terrarium.


  • Water your terrarium carefully. Too much water risks causing roots to rot and eventually killing the plants. Water infrequently, especially in a closed terrarium.
  • Check the moisture level of the soil periodically and water according to plant needs. The frequency of watering depends on several factors, such as the size of the container, the type of terrarium (open or closed), lighting and temperature conditions, the nature of the substrate and the type of plants grown.
  • Add a small amount of water at a time, to avoid an excess. The soil should be slightly moist, not soggy. In addition, water should not accumulate in the drainage layer, otherwise it will be useless.
  • Adjust the humidity level as needed by opening and closing the terrarium. It is normal for a little condensation to form occasionally on the walls of a closed terrarium, but constant or excessive water droplets often indicates overwatering. If this happens, open the lid and allow the terrarium to dry out a bit.
  • Water insectivorous plants with rainwater or distilled or purified water, as they’re highly sensitive to minerals that water contains.

(Tip: If you’ve inadvertently overwatered your terrarium, you can use a turkey baster to try to remove the excess water.)


  • Fertilize plants grown in terrariums sparingly to prevent them from growing too quickly and requiring frequent pruning.
  • Apply fertilizers only once a month during periods of active growth, generally from March to October. Natural fertilizers are a good choice.

Special advice for insectivorous plants

Insectivorous plants require very little fertilizer, and fertilization is even not recommended in some cases: for example, butterworts (Pinguicula), sundews (Drosera) and the Venus flytrap (Dionaea muscipula).

Never apply fertilizers directly to the soil, as this can burn the roots. As well, the acidity of the substrate hinders the assimilation of certain minerals. Instead, spray the fertilizer on the leaves or in the traps of the plants, diluting it beforehand to a quarter of the recommended dose or even more, depending on the species.

You can occasionally offer small insects to your plants, although this isn’t necessary. Dried insects are available in some specialized shops. Never feed meat to insectivorous plants.


  • Prune or pinch plants that become too bulky.


  • Regularly clean the plants, removing dead leaves and branches to prevent diseases.
  • Also be sure to keep the glass walls clean so as not to reduce the light that the plants need. Remove dirt with a lint-free cloth and water, ideally distilled or deionized.


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