- Understand the key differences between open and closed terrariums
- Learn how humidity and air flow impact plant health
- Discover the best plants for open vs. closed setups
- Get a step-by-step guide to building each terrarium type
- Explore container and substrate options tailored to your needs
- Find out which type suits your space, lighting, and care routine
Introduction
Terrariums are miniature indoor gardens housed in glass containers, offering a unique and stylish way to bring nature indoors. Whether displayed on a desk, shelf, or windowsill, they serve as both living art and a fulfilling plant care hobby.
As interest in indoor greenery and low-maintenance houseplants grows, terrariums have made a comeback. But not all terrariums are created equal. Understanding the distinction between open and closed terrariums is essential—not just for plant health, but also for creating the aesthetic and effort level that fits your lifestyle.
Understanding the Difference Between Open and Closed Terrariums
Open Terrariums
- Use containers with an open top, like bowls, vases, or trays.
- Air flows freely, which prevents humidity buildup.
- Ideal for plants that dislike excess moisture.
Closed Terrariums
- Completely sealed with a lid or stopper.
- Moisture is trapped and recycles through evaporation and condensation.
- Creates a natural, humid microclimate perfect for tropical species.
Pros and Cons of Each Type Regarding Humidity and Care
| Feature | Open Terrarium | Closed Terrarium |
|---|---|---|
| Humidity | Low; moisture evaporates quickly | High; self-regulating moisture cycle |
| Watering Needs | More frequent (weekly or biweekly) | Infrequent (monthly or less) |
| Best Plant Types | Cacti, succulents, air plants | Moss, ferns, tropical foliage |
| Maintenance Level | Moderate; more watering | Low; but needs occasional monitoring of humidity |
| Risks | Soil dries fast; risk of under-watering | Risk of mold if overwatered or sealed too tight |
Choosing Plants for Open Terrariums
Best Plant Types
- Succulents: Echeveria, sedum, jade plants
- Cacti: Moon cactus, haworthia, golden barrel
- Air Plants: Tillandsia species (require no soil)
Care Considerations
- Provide bright, indirect to direct light
- Use soil with excellent drainage such as cactus mix
- Water deeply but sparingly—wait until soil is fully dry
- Don’t mix succulent types with high-humidity plants
Choosing Plants for Closed Terrariums
Best Plant Types
- Ferns: Maidenhair fern, button fern
- Mosses: Sheet moss, cushion moss
- Tropical Miniatures: Fittonia (nerve plant), pilea, peperomia
Care Considerations
- Thrive in high humidity and moderate to low light
- Minimal watering—often every 3–6 weeks
- Watch for excess condensation; open briefly to adjust
- Prune frequently to avoid overcrowding
For more on how mini-ecosystems work, check out our guide to closed terrariums here.
Selecting Appropriate Containers and Materials for Both Styles
Open Terrariums
- Use containers with wide openings like bowls, geometric glass vessels, or dishes
- Allow easy access for maintenance and airflow for plant health
Closed Terrariums
- Ideal containers include glass jars with lids, bell jars, or cloches
- Ensure the lid fits tightly to retain moisture—avoid gaps
Material Considerations
- Glass is best for visibility and light control
- Avoid porous materials like wood or unsealed metal which can degrade or affect humidity
Layering Drainage and Substrates According to Moisture Needs
| Layer | Open Terrarium | Closed Terrarium |
|---|---|---|
| Bottom Layer | Pebbles or stones for drainage | Pebbles or LECA for drainage |
| Second Layer | Activated charcoal to reduce odor and bacteria | Activated charcoal to balance moisture |
| Top Layer | Cactus/succulent mix (very well-draining) | Moisture-retentive potting soil |
Tip: Use tweezers or long-handled tools to carefully place plants and decorations inside narrow containers with precision and cleanliness.
Care Routines: Watering, Ventilation and Light Management
Open Terrarium Care Routine
- Watering: Every 1–2 weeks, only when soil is fully dry
- Light: Bright, indirect to direct sunlight
- Ventilation: Not required due to open container
Closed Terrarium Care Routine
- Watering: Once every few weeks or when soil looks dry
- Light: Indirect sunlight—avoid direct rays to prevent overheating
- Ventilation: Open periodically to reduce excess humidity or fogging
Conclusion: Selecting the Right Terrarium for Your Home
A well-constructed terrarium does more than brighten a room—it fosters a tiny, self-sustaining ecosystem. Whether you prefer the drought-tolerant flair of succulents or the lush jungle vibe of humid mosses and ferns, the type of terrarium you choose should align with your space and schedule.
Recap
- Open terrariums suit dry, sunny spots and low-humidity plants like cacti
- Closed terrariums thrive in shadier areas with high-humidity, tropical flora
Action Tip
Match your terrarium type with your lighting conditions and how hands-on you want to be. Open types need more frequent care, while closed ones offer a more “set-and-forget” experience.
Ready to build your own? Dive into our full build walkthrough for closed terrariums here.
