Introduction: Mason Jar Terrarium

I have always wanted to make a terrarium. During the lockdown period, I got the opportunity to make one using materials available at home. This is my first try in making a terrarium, so I did a small research on terrariums and decided to make a closed terrarium since I was able to find the required plants in my backyard.

This instructable is about making a closed terrarium in a mason jar.


  • Glass jar.
  • Pebbles / stones / gravel.
  • Activated charcoal (if you don’t have activated charcoal then you will need regular charcoal and calcium chloride)
  • Soil.
  • Plants.
  • Tweezers.

Step 1: Making Activated Charcoal

Activated charcoal is a fine black powder made from bone char, coconut shells, peat, petroleum coke, coal, olive pits or sawdust processed at high temperature.

Why do we need activated charcoal for our terrarium?

Terrariums are ecosystems and in every ecosystem leaves fall out, plants die and organic matter will also degrade. Decaying organic material releases unpleasant gasses and toxins that can be harmful to your plants (and your nostrils). Increased chances of harmful rot in your terrarium. Potential overgrowth of unwanted moulds and mildew.

The charcoal's porous texture has a negative electrical charge, which causes it to attract positively charged molecules, such as toxins and gases

So adding charcoal will be healthy for your terrarium.

  • Burn coconut shell.
  • Wash the charcoal.
  • Let it dry naturally.
  • Mix powdered calcium chloride with water.
  • Pour the charcoal into the calcium chloride solution.
  • Close it with a lid. And keep like that for 24hrs.
  • After 24hrs some impurities and cellulose will be floating on the surface, remove it.
  • Then remove the excess water from the solution.
  • Lay it out in your baking tray and bake in your oven for 2hrs at 210 degree F or 100 degree C.

After this, your activated charcoal will be ready. You can resize it accordingly.

Step 2: Choosing Type of Terrarium

There are 2 types of terrarium open and closed.

Type of your terrarium can be decided according to the plants you intend to use for the terrarium.

If your plants like moisture and humidity, you need a closed terrarium. If your plants don’t, you need an open terrarium.

Here I am using plants which need moisture so I am going to build a closed terrarium.

Step 3: Collecting Plants, Soil and Stones

All the plants I wanted in my terrarium was in my backyard it was easy to get. I am using

  • Moss - Tortula Ruralis(star moss)
  • Fern - Nephrolepis Exaltata (sword fern)
  • Biophytum Sensitivum (Little tree plant)

I got some small stones which can be used for the base. This base will act as a reservoir for the terrarium.

For soil, Take normal soil which is available to you. Mix the activated charcoal in soil. Soil is ready to use.

Step 4: Selecting Container

Containers with a uniform shape (e.g. a box or cylinder) or a broad curve (e.g. a globe) tend to provide a consistent shape. Since I am just getting started with the terrarium, I’m going for a container with a nice wide opening to give you lots of space to work. So here I am using a mason jar for the terrarium.

Step 5: Making Terrarium

we’re going to create a false bottom for a terrarium, which is a reservoir created by a layer of large rocks, pebbles, or other such objects. Here the water can drain from the substrate before evaporating to perpetuate the water cycle. A simple pebble layer will suffice.

  • First, create a pebble layer.
  • Then add the soil on top of the pebble layer.
  • Plant your plants accordingly. Start with bigger plants. Then you can arrange the rest of your plants.
  • Finally, add moss to cover exposed earth, it will give a great look for your terrarium.
  • Now we have to water our terrarium. Misting plants is one way to avoid over-watering.
  • Now we can close the lid.

Closed terrarium is ready.

Step 6: Maintenance

Remove your terrariums lid once a week for up to 15 minutes to let in fresh carbon dioxide.

If humidity is more than required, there is a potential for the growth of mould. To prevent this we can use small bugs. They will prevent the growth of mould. You can use either Springtails (Collembola sp) or Dwarf Isopods. They are easily available to buy.

Hope you enjoy making the terrarium.

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