Sealed Terrariums

Posted on February 28th, 2022

People have definitely heard the word “Terrarium” before but might not understand what exactly goes into making one. Terrariums are self-sustaining ecosystems that generate their own climate, water cycle, and environment within a self-contained container. We are here to help you construct the perfect terrarium for your home!

Terrariums are miniature Gardens enclosed in glass or clear plastic. Access to outside air is typically strictly limited or non-existent (in closed terrariums) Moisture by plants is given off through transpiration, which then condenses on the glass walls and runs down to moisten the soil. The key to repeating this process and having your terrarium become self-sustaining is to create a seal at the top so that moisture and humidity do not escape the confines of the glass container.

Step 1: Picking your Container

A good terrarium container is anything that is clear and has a cover, or a cover can be placed on it. Look for the perfect glass or plastic container that matches the decor of your home. The opening of the glass can be big or small, depending on what size plants you prefer to add. Many household items make perfect terrariums such as glass bottles, jars, empty candle holders, etc.

Step 2: Constructing your Terrarium

The key to making a healthy environment in your terrarium is to work in layers. Each layer of a terrarium serves a specific purpose for the transpiration cycle to become self-sustaining.

  • First, add 1/2-1″ of coarse sand, gravel, or pebbles. This is the drainage layer that will capture excess moisture.
  • Add a thin layer of charcoal granules. Charcoal keeps odors from developing.
  • Add a layer of Sphagnum Moss. Moss keeps soil from seeping into the drainage layer.
  • Add 1/2-1″ of well-draining, fertile potting soil.

Step 3: Build your Terrarium

No special tools are needed to plant your terrarium, silverware will work just fine (unless you are planting in a narrow opening or a long-necked bottle). You should begin by adding your preferred plants. Simply dig a small hole and use a spoon to cover the roots with soil. For a more interesting design, use an odd number of plants. this will heighten the organic nature of the terrarium. Try not to crowd the plants too much as they will grow into each other.

After you have added your plants, there are a number of different decorative options that can be added to a terrarium to really enhance the aesthetic you are going for. If you are trying to create a more naturalistic environment, sticks and rocks are a great addition. Some people may prefer to add small statues or figurines to create a more fantastical aesthetic.

Once you have decides on your terrarium’s aesthetic, add water to a spray bottle and spray the sides of the container and the leaves of the plant. Once complete, seal your terrarium and observe it for several days to ensure the water level is enough to generate moisture without drying out. If you feel you need more moisture, simply spray more water and reseal. Once the cycle is successful, place your terrarium in bright indirect light, as direct sunlight can potentially destroy the internal temperature of your terrarium.

These terrariums should last for months if not years when done correctly!

If you are having difficulty sourcing the substrate materials for your terrarium, we have everything you need here at the garden center! Simply stop by our North Branford location and we will help you with whatever you need.