Creating your first closed terrarium is easier than you might think. These self-sustaining glass ecosystems bring a miniature green world indoors with minimal maintenance. Perfect for Canadians in small apartments or cold climates, closed terrariums provide beauty, stress relief, and a touch of nature anywhere—from desks to shelves. This step-by-step guide will show you how to build your first closed terrarium, covering all materials, setup instructions, and essential care tips for long-term success.

What Is a Closed Terrarium?

A closed terrarium is a sealed glass container that sustains plants in a self-contained environment. Its lid allows the system to recycle moisture: water vapor from the soil and plants condenses on the glass and then returns to the soil like rainfall. In this way, the miniature ecosystem maintains its own natural water cycle.

The sealed environment of closed terrariums distinguishes them from open terrariums because they need less frequent watering and air exchange. The closed terrarium environment provides optimal conditions for tropical plants such as ferns and mosses, and fittonias, which thrive in humid environments.

The closed terrarium system provides Canadians with a solution to maintain indoor plants throughout every season because they do not require outdoor access.

Why Build One?

The process of creating your own closed terrarium system provides multiple advantages to users.

• The proper setup of these containers requires minimal watering and care maintenance.
• The compact design makes them ideal for residents of apartments, condos, and small houses.
• Scientific research demonstrates that indoor plants create stress relief while improving emotional states.
• The process of creating a terrarium lets you construct your personal miniature universe.
• The decorative appearance of these containers makes them excellent additions to coffee tables and office desks, and shelves.

What You’ll Need

Begin your project by collecting these fundamental materials.

• A glass container with a lid serves as the base for your terrarium project.
• Small stones or pebbles, required for drainage.
• Activated charcoal serves two purposes by maintaining soil freshness while blocking unpleasant odors.
• The drainage layer needs protection from soil contamination through the use of fiberglass mesh or landscape fabric.
• Select a potting soil that matches the requirements of tropical plants for your terrarium.
• Select plants from the following list: Ferns, mosses, nerve plants (fittonia), and small tropical species.
• Optional decorations include small figurines and decorative rocks, and driftwood pieces.
• A spoon or chopsticks, or long tweezers serve as planting tools for your terrarium project.

Best Plants for Closed Terrariums

A closed terrarium requires specific plants that can tolerate its humid conditions. Select plants that thrive in tropical environments similar to their natural habitats, which exist in tropical regions with moist shaded areas. The following plants work well in closed terrariums:

• Mosses: These plants require minimal care while providing lush coverage for terrarium floors.
• Ferns, including maidenhair and button ferns, thrive best in humid environments.
• Fittonia (Nerve Plant): Known for its colourful, veined leaves.
• Pilea: Compact and adaptable to moist environments.
• Peperomia: The small-leaved varieties of this plant succeed well in terrarium environments.
• Mini orchids require advanced care, but their elegant appearance makes them suitable for experienced growers.

Succulents and cacti should be avoided because they need dry environments, which will cause them to rot inside a sealed terrarium.

Step-by-Step: Building Your Closed Terrarium

1. Choose Your Container

Select a glass container that matches your available space and personal design preferences. Mason jars produce a rustic appearance, but tall curved glass containers create a sophisticated look. A lid must be present on the container to maintain moisture inside the terrarium. The size of your terrarium affects plant growth because larger containers provide better space for roots and create stable ecological systems.

2. Add the Drainage Layer

Begin by placing a 2–3 cm deep layer of small pebbles or stones at the base of the container. The drainage layer stops water from accumulating in the soil, which helps prevent root rot from occurring. A 2–3 cm deep layer of drainage material should be used.

3. Add the Fiberglass Mesh Divider

The drainage layer requires a fiberglass mesh (or landscape fabric) to be placed on top of it. The divider prevents soil from sinking into the stones and charcoal, which helps maintain the terrarium's organization and operational state throughout time. The mesh needs to be cut to match the container dimensions before you press it down into position.

4. Sprinkle Activated Charcoal

The activated charcoal layer placed on top of the mesh maintains freshness and prevents mold growth and unpleasant odors in the terrarium environment.

5. Add Potting Soil

The soil layer should be between two to three inches deep, depending on your container size. Tropical houseplant soil mixes work best. Create small dips where each plant will go.

6. Arrange Your Plants

Start by placing your largest plants into the soil before adding smaller plants to the space. Mosses and smaller plants should be used to fill any remaining spaces. The plants need enough space to breathe, so overcrowding should be avoided. Press the moss gently onto the soil surface to help it establish itself.

7. Add Decorative Touches

You can express your creativity at this point. The addition of tiny stones and driftwood, and small figurines enables you to personalize your terrarium design. People choose to add miniature benches and fairy garden decorations for whimsical effects, but others choose natural woodland elements for their terrariums.

8. Add Water in Small Amounts

Water the soil with a light spray or a minimal amount of liquid. The soil needs to stay moist but not soggy because this will activate the ecosystem. The main mistake new terrarium owners make involves excessive watering of their plants.

9. Seal It Up

The container needs its lid to be placed on before nature takes over the process. The glass will develop condensation during the first few days, which indicates that the ecosystem process is functioning properly. When the glass becomes excessively foggy, you should open the lid for several hours to achieve moisture equilibrium.

Caring for Your Closed Terrarium

The maintenance requirements for closed terrariums remain minimal, but they require occasional monitoring. The following instructions show you how to properly care for your terrarium:

Light: Place your terrarium under conditions of bright light, which should not directly hit the glass surface. The glass surface will become overheated when exposed to direct sunlight, which will cause damage to your plants.

Moisture: Check for excessive glass fogging by opening the lid for short periods to release moisture. Check the soil moisture by adding a few drops of water when it appears dry.

Pruning: Regular plant maintenance requires trimming plants when they reach excessive height or when their growth causes overcrowding between plants.

Cleaning: Regular glass surface cleaning will maintain both clarity and visual appeal of your terrarium.

Common Mistakes to Avoid

Your terrarium will thrive when you stay away from these common mistakes:

• The addition of excessive water causes the soil to become waterlogged, which results in root decay. The amount of water should always be minimal during watering.
• Succulents, together with cacti, will perish when placed inside the humid environment of a closed terrarium.
• The intense sun rays passing through glass create heat magnification that damages plants.
• The absence of charcoal creates conditions for mold growth and unpleasant odors to develop.
• Plants that are packed too tightly together will struggle to survive because they need sufficient space to thrive.

Extra Tips for Success

• Natural elements such as small stones, driftwood, and mossy bark pieces create a forest-like charm and add visual appeal to your miniature garden.
• Position your terrarium in a spot where you can see it frequently, but choose a location that protects it from direct sunlight exposure.
• Turn your terrarium periodically every few weeks to promote balanced plant development.
• Check the seal of your lid because an open seal will cause rapid drying, but a tight seal may create excessive water accumulation. Make adjustments to the lid seal according to your needs.
• Create visually appealing base layers through the combination of colorful sand with various stone textures.
• The combination of leafy plants with soft moss creates visual depth, which enhances the natural appearance of your miniature garden.

Your Miniature Ecosystem Awaits

Creating your first closed terrarium is more than a DIY project—it’s a chance to build a self-sustaining indoor garden that brings life, beauty, and tranquility to any space. With minimal upkeep, your terrarium recycles water, nurtures plants, and thrives year-round, even in small apartments or cold climates.

Get Started Today

Learn everything from setup to maintenance with The Ultimate Beginner’s Guide to Closed Terrariums and create your own thriving miniature indoor ecosystem!

FAQs About Closed Terrariums

Can I use succulents in a closed terrarium?

No. Succulents and cacti require dry conditions and will rot in a humid, sealed environment.

How often should I water my closed terrarium?

Usually, once every few weeks, or only when the soil appears dry. Observe condensation on the glass for guidance.

Can I place my terrarium near a sunny window?

Avoid direct sunlight. North or east-facing windows provide gentle, indirect light ideal for most terrarium plants.

How do I maintain plant health inside the terrarium?

Rotate the container periodically, trim overgrown plants, and adjust the lid seal to control moisture levels.