It may happen, you may end up with some mold in your terrarium. Here are some tips and techniques to help you control or eliminate this problem.

Here is a picture of a terrarium with mold in it.

Preventing Mold:

Let me just give you some tips and guidelins on how to reduce the prospect of mold growing in your terrarium.

• Use charcoal in the soil. This often helps discourage mold growth. What you do is put a thin layer of charcoal just below the soil. This can be a big help. Usually about a 1/4 to 1/2 inch layer is good. This helps keep the terrarium clean by filtering the water.
• Go easy on the watering! (If it is a closed terrarium) When you first water the terrarium go easy on the water. Too much water is one of the biggest causes of mold growth.
• Only use fresh and hardy plants! Inspect any plants before putting them in the terrarium. If there is any mold at all on them you should either thoroughly remove it. Better yet prune the affected areas. Or even better yet just don't use the plant.

Removing or eliminating mold:

• If you have a closed terrarium and it is developing mold the water inside might be too abundant. Remove the cap off the top for a few days to reduce the water and promote some air circulation. This might correct the situation. It is a good option.
• Also - if there is limited mold you can use some tools to prune away the affected area. Still keep the cap off to reduce the humidity and water inside.
• Also- If one or two plants are affected you might want to just remove them from the terrarium.
• While you are removing or pruning plants you should remove any buds of mold that is on the soil. And irrigate the soil a bit by stirring the surface around. Scratch it to get air to it.

Using Chemicals -

• This is a bit of a tricky area. Generally I am against using any kind of chemicals in a closed terrarium. There is risk of harming the mini eco-system in there. If you do use some kind of a cleaner or chemical try to use as little as possible. The thing about it is that you want to kill the mold, but there is a chance that you will also kill other things.
• Tip from A web visitor: If you use high strength peroxide it will kill mold and bacteria and give the root zone oxygen. Some are 35% some are 22% but all bottles have instructions for mixing. And you can get it at any hydroponic shop or online. Spray application would be the way to go. He tells us a bit more:

  Yes hydrogen peroxide. the 3% stuff you get at the store is to watered down though. You'll need to get the heavy concentrate from a horticulture/hydroponic store.

  There's a few brands and different strengths. It doesn't go below 26% for the heavy concentrate and its not a huge deal if its 36% or 25% or 30%. I think its more for marketing and to up the price if the % is higher.

  Just follow the directions and don't use it as a foliar feed.

  Roots take in oxygen and hydrogen peroxide cleans areas as well.

This picture shows using a grabber tool to get hold of the moldy plant and removing it from the terrarium.

In a terrarium like this the grabber tool works really well for removing plants.

Apothecary Jar Terrariums

Here are three wonderful terrariums made by a web visitor (Linda D.) Among other things she used peppermint plants and moss which make a wonderful combination. Check out more pictures and some advice here: The Apothecary terrariums

The Terrarium Room

Wouldn't this be great? It's like bringing a miniature exotic garden right into the house. It is no doubt a wonderful place to relax and find some quiet time and a little bit of communing with nature. Larger Picture and more here: The terrarium Room