Create Your Garden

Closed Terrarium 101: Maintenance, Plants, and More

Learn how to create and maintain a closed terrarium with ideal plants for a self-sustaining indoor garden.

Closed Terrarium, Terrarium Plants, Terrarium

What is a Closed Terrarium?

A closed terrarium is essentially a self-contained ecosystem, typically housed within a sealed glass container that provides an ideal environment for growing a variety of moisture-loving plants. This type of terrarium is both a functional and decorative element that simulates a natural environment by creating a miniature greenhouse effect.

How Does It Work?

The fundamental principle behind a closed terrarium is the creation of a small-scale water cycle. Here’s how it operates:

Light: When placed in indirect light, the sunlight warms the air and soil within the terrarium, causing water to evaporate from the soil and plant leaves.

Condensation: As the warm, moist air rises and comes into contact with the cooler glass walls, it condenses into droplets.

Precipitation: These droplets eventually become heavy enough to trickle down the sides of the glass, effectively “raining” back into the soil.

This cyclical process means that the terrarium can often sustain itself with very minimal intervention, as it constantly recycles the moisture within.


Low Maintenance: Due to their self-sustaining nature, closed terrariums require significantly less watering compared to traditional houseplants. This makes them an ideal choice for those who desire greenery without a high-maintenance commitment.

Microclimate Creation: Closed terrariums create a stable, humid microclimate that is perfect for tropical plants, such as ferns, mosses, and orchids, which may otherwise struggle in typical home environments.

Aesthetic Appeal: With their lush greenery encased in glass, closed terrariums add a unique botanical aesthetic to any space, serving as living art pieces that invite the beauty of nature indoors.

In summary, closed terrariums offer an engaging way to integrate green living into urban settings, requiring little space and care while providing significant visual and environmental benefits. They encapsulate a piece of the natural world, making them not only a gardening venture but also a conversation starter and a focal point in interior design.

Ideal Plants for a Closed Terrarium

Since closed terrariums maintain a high humidity level, they are best suited for tropical plants that thrive in moist environments.

How to Make a Closed Terrarium

Creating a closed terrarium is a rewarding project that brings a bit of nature indoors and requires minimal maintenance once set up. Here’s a step-by-step guide on how to create your own closed terrarium:

Materials Needed:

  • Glass Container: Choose a clear glass container with a lid. This can be a jar, bottle, or a specially designed terrarium container with a removable cover.
  • Gravel or Small Stones: This layer provides drainage, preventing excess water from sitting in the soil.
  • Activated Charcoal: A thin layer of activated charcoal keeps the water fresh and prevents mold and bacterial growth.
  • Sphagnum Moss: This layer prevents the soil from mixing into the drainage layer of rocks and charcoal.
  • Potting Soil: Use a high-quality potting mix suitable for the types of plants you are using. For most tropical plants, a general-purpose potting soil is adequate.
  • Terrarium Plants: Choose small plants that thrive in high humidity and low light. Ferns, mosses, and small tropical plants are ideal.
  • Decorative Elements: Consider adding rocks, wood, or figurines to enhance the aesthetic of your terrarium.
  • Tools: You might need long tweezers or chopsticks to place plants and decorative items, and a funnel or spoon to add soil and charcoal.

Steps to Create a Closed Terrarium:

  • Prepare the Container: Clean your glass container thoroughly to remove any dust or residues that might affect plant health.
  • Create a Drainage Layer: Add a layer of gravel or small stones at the bottom of the container to facilitate drainage and prevent root rot.
  • Add Activated Charcoal: Spread a thin layer of activated charcoal over the stones to help purify the water and control any odors.
  • Add Sphagnum Moss: Place a layer of sphagnum moss on top of the charcoal to keep the next layer of soil from sifting down into the charcoal and stones.
  • Add Potting Soil: Add enough potting soil on top of the moss to support the roots of the plants you have chosen. The amount will depend on the size of your container and the plants’ root systems.
  • Plant Your Terrarium Plants: Make small holes in the soil and gently insert your plants. Use tools like tweezers or chopsticks if the container’s opening is narrow. Arrange the taller plants towards the back or center, and lower-growing plants in the front.
  • Add Decorations: Place any decorative stones, pieces of wood, or figurines in your terrarium to enhance its appearance.
  • Water Lightly: Mist the plants lightly with water to settle the soil around the roots and add some initial moisture.
  • Close the Lid: Seal your terrarium with its lid. Watch the terrarium over the next few days; if there is excessive condensation, open the lid to let some moisture escape. This balances the environment inside.

Closed Terrarium, Terrarium Plants, Terrarium

Closed Terrarium: Care and Maintenance

Caring for a closed terrarium is relatively straightforward, thanks to its self-sustaining nature. However, regular monitoring and minimal maintenance are key to keeping your miniature ecosystem thriving over the long term. Here are essential tips for the care and maintenance of a closed terrarium:


  • Ideal Light Conditions: Place your closed terrarium in a spot where it will receive indirect light. Direct sunlight can cause the interior to become too warm, leading to overheated plants and excessive condensation. A location near a window with filtered light or artificial lighting that mimics natural light is optimal.
  • Avoid Direct Sunlight: Direct sunlight can essentially turn your terrarium into a greenhouse, with temperatures high enough to harm the plants inside.


  • Minimal Watering Needed: The beauty of a closed terrarium is that it recycles moisture. Water evaporates from the soil and plant leaves, condenses on the glass, and trickles back into the soil, creating a self-sustaining water cycle.
  • Observation Is Key: If you notice the soil looks excessively dry or the glass stops fogging up, it’s a sign that you might need to add a small amount of water. Conversely, too much condensation can mean too much water; slightly open the lid for a few hours to let some moisture escape.

Air Circulation

  • Occasional Venting: Even though it’s a closed environment, occasional airing can help refresh the air inside the terrarium. Open the lid once a month for a few hours to allow exchange of air which helps prevent mold growth and replenishes oxygen levels.


  • Glass Cleaning: Keep the glass clear both inside and out. Condensation can leave mineral deposits on the glass. Clean the interior gently with a soft cloth to avoid disturbing the plants. Use a glass cleaner on the outside to ensure maximum light penetration.
  • Remove Debris: Regularly remove any fallen or dead leaves and other debris to prevent mold and bacterial growth.

Plant Health

  • Pruning and Trimming: Prune any overgrown or dead plant parts to maintain aesthetics and prevent decay inside the terrarium. Healthy, well-trimmed plants are less susceptible to diseases.
  • Watch for Pests and Diseases: Inspect your plants regularly for signs of pests or diseases. Common issues like mold can often be managed by improving air circulation or adjusting moisture levels.

Soil and Fertilization

  • Soil: The closed environment means nutrients are recycled, so additional fertilizer is rarely necessary. If you do fertilize, do so very sparingly using a diluted solution.
  • Avoid Over-fertilizing: Excess nutrients can lead to rapid plant growth, which isn’t ideal in a confined space.

Monitoring and Adjustments

  • Regular Checks: Observe your terrarium regularly for signs of stress in plants or improper water levels. Each terrarium is unique, and adjustments might be necessary depending on how the system stabilizes.
  • Seasonal Adjustments: The amount of light and ambient temperature may change with the seasons, so adjustments may be necessary to maintain the terrarium’s balance throughout the year.

A well-maintained closed terrarium can provide years of enjoyment with relatively little intervention. Observing and understanding the unique dynamics of your miniature ecosystem will allow you to make necessary adjustments and keep it thriving.

Discover These Helpful Guides for Further Reading

While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.

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