Closed vs Open Terrariums: What's the Difference?

Comparison of a closed terrarium with moss and tropical plants and an open terrarium with succulents, stones and dry materials


Choosing Your Terrarium ?

Choosing between a closed and an open terrarium is not about style.
It is about how you want to live with the system.

Both are terrariums.
They behave very differently.

Understanding the difference removes most beginner mistakes before they happen.

1. What Makes a Terrarium “Closed” or “Open”?

The difference is simple:Comparison of closed and open terrariums with different humidity, ventilation and plant conditions

🌱 Closed Terrarium

  • Sealed or mostly sealed

  • High, stable humidity

  • Minimal airflow

  • Self-contained water cycle

🌵 Open Terrarium

  • No lid or permanently open

  • Constant airflow

  • Humidity escapes

  • Requires occasional watering

Everything else—plants, care, behavior—follows from this.

2. Closed Terrariums — How They Work

A closed terrarium functions as a mini ecosystem.Water cycle in a closed terrarium showing evaporation, condensation and water returning to the substrate

Water:

  • evaporates

  • condenses on the glass

  • returns to the soil

This cycle allows the system to regulate itself when built and placed correctly.

Best suited for:

  • Moss

  • Small ferns

  • Selaginella

  • Fittonia (used sparingly)

What closed terrariums are good at:

  • Staying stable

  • Needing very little care

  • Creating calm, slow change

What they are NOT:

  • Fast-growing

  • Adjustable on demand

  • Compatible with dry-air plants

Closed terrariums reward restraint and observation.

3. Open Terrariums — How They Work

Open terrariums behave more like shallow planters.

Because air moves freely:

  • moisture escapes

  • watering is sometimes needed

  • humidity does not build up

Best suited for:

  • Succulents

  • Cacti

  • Air plants (Tillandsia)

What open terrariums are good at:

  • Brighter placements

  • Dry-air plants

  • Visual flexibility

What they are NOT:

  • Self-sustaining

  • Humidity-stable

  • Compatible with moss ecosystems

Open terrariums require light interaction, but still far less than houseplants.

4. Maintenance Comparison (Simple & Honest)

Closed Terrariums

  • Watering: very rare

  • Light: bright, indirect

  • Condensation: normal and expected

  • Intervention: minimal

Open Terrariums

  • Watering: occasional

  • Light: brighter tolerance

  • Condensation: usually absent

  • Intervention: light but regular

Neither is “better”.
They are simply different systems.

Whether your terrarium is closed or open, the basic principle remains the same: observe the condition of the system before taking action. For a complete practical care routine, see our [complete guide to caring for a terrarium].

5. Which One Is Right for You?

Choose a closed terrarium if:

  • you want minimal care

  • you enjoy slow change

  • you prefer observation over action

  • you are drawn to forest-floor aesthetics

Choose an open terrarium if:

  • you enjoy light interaction

  • you prefer succulents or air plants

  • your space has brighter light

  • you want more visual control

6. Common Mistakes to Avoid

❌ Putting succulents in closed glass
❌ Expecting moss to thrive in open air
❌ Treating both systems the same
❌ Choosing by looks alone

Plants fail when systems are misunderstood.

7. The MossBoss Principle

A terrarium succeeds when:

  • the system matches the plants

  • the plants match the environment

  • the owner understands when not to act

Closed or open, the goal is the same:
balance over maintenance.

🌿 Related Guides

Discover tips, guides, and inspiration for your terrarium journey