Terrarium What Plants to Use – Expert Selection Guide
To choose the right plants, first identify if your terrarium is closed or open. Closed systems require high-humidity tropical plants like ferns and mosses, while open systems suit succulents and cacti that prefer dry air.
Starting a miniature indoor garden is an exciting transition for many hobbyists who already enjoy the art of aquascaping. Understanding terrarium what plants to use is the most critical step in ensuring your glass-enclosed ecosystem thrives for years rather than weeks.
Selecting the wrong species can lead to rapid decay or overgrown glass that obscures your hard work. By focusing on the specific environmental needs of different flora, you can create a balanced world that mimics the beauty of a natural forest floor or a desert landscape.
Whether you are repurposing an old glass tank or starting with a dedicated glass jar, the rules of biology remain the same. Matching the plant to the container type is the foundation of all successful builds.
The Core Framework: Closed vs. Open Systems
The most important factor in deciding terrarium what plants to use is the type of container you have chosen. A closed terrarium creates a self-sustaining cycle where water evaporates, condenses on the glass, and falls back to the soil.
This process, known as evapotranspiration, maintains a constant high-humidity environment. Tropical plants thrive here, as the moisture levels remain high and the temperature stays relatively stable.
Open terrariums, on the other hand, do not have a lid and allow for constant air circulation. These are designed for plants that require lower humidity and faster-drying soil to prevent fungal issues.
| Feature | Closed Terrarium | Open Terrarium |
|---|---|---|
| Humidity Level | High (70% – 90%+) | Low (Ambient Room Air) |
| Ideal Plant Types | Ferns, Mosses, Tropicals | Succulents, Cacti, Air Plants |
| Watering Frequency | Rarely (Every few months) | Frequently (Weekly or Bi-weekly) |
| Air Circulation | Limited / Recycled | High / Constant |
Common Mistake: Never mix succulents and tropical ferns in the same container. The high humidity required by the fern will cause the succulent to rot, while the dry air needed by the succulent will wither the fern.
Top Tropical Plants for Closed Terrariums
When considering terrarium what plants to use for a closed environment, you want species that enjoy “wet feet” and damp air. These plants are often found in the understory of rainforests where light is filtered and humidity is thick.
Nerve Plants (Fittonia albivenis)
Fittonia albivenis is perhaps the most iconic terrarium plant due to its striking leaf venation. These plants come in shades of white, pink, and bright red, providing a much-needed pop of color against green mosses.
They are excellent indicators of moisture levels because they will visibly wilt or “faint” when the soil gets too dry. Once watered, they perk back up within hours, making them great for beginners learning to balance hydration.
Peacock Ferns and Mosses
Selaginella uncinata, also known as the Peacock Fern, is a stunning choice for ground cover. It features iridescent blue-green foliage that seems to glow under artificial LED lighting.
Mosses are also essential for a natural look, acting as a living carpet that retains moisture. They help stabilize the microclimate and provide a soft texture that bridges the gap between hardscape and larger plants.
The Friendship Plant (Pilea involucrata)
Pilea involucrata is highly valued for its deeply textured, velvety leaves. The bronze and green hues add a sophisticated layer of depth to the mid-ground of your display.
This species stays relatively compact but responds well to pruning if it begins to touch the glass. It is a hardy survivor that thrives in the consistent warmth of a closed vessel.
Unique Specimen Plants for Visual Interest
If you want your display to stand out, you should look for “statement” plants that offer unique shapes. These species often act as the focal point of the entire arrangement.
The Little Tree Plant (Biophytum sensitivum)
Biophytum sensitivum is a fascinating addition because it looks like a miniature palm tree. It rarely grows taller than a few inches, making it perfect for small-scale landscapes.
Interestingly, its leaves react to touch or changes in light by folding downward. This kinetic movement adds an interactive element to your indoor garden.
Earth Stars (Cryptanthus bivittatus)
Cryptanthus bivittatus is a member of the bromeliad family that grows terrestrially. Unlike many other bromeliads, it prefers to have its roots in a moist substrate rather than clinging to wood.
Its star-shaped growth habit and striped foliage make it an excellent choice for the foreground. It is a slow grower, which is a vital trait when deciding terrarium what plants to use in confined spaces.
Pro Tip: Use long-handled aquascaping tweezers to plant small species like Cryptanthus. This prevents you from crushing the delicate leaves or disturbing the surrounding substrate layers.
Essential Substrate and Drainage Components
The health of your plants depends entirely on what lies beneath them. Because terrariums lack drainage holes, you must build a system that prevents water from pooling around the roots.
Creating the Drainage Layer
Start with a layer of Expanded clay aggregate (often called LECA) or small gravel at the bottom. This creates a reservoir where excess water can sit without touching the soil.
Above this, place a fine mesh screen or a layer of dried sphagnum moss to act as a barrier. This prevents the soil from washing down into the drainage layer and becoming a muddy mess.
The Role of Activated Carbon
A thin layer of Activated carbon should be placed over the drainage barrier. This material is essential for filtering the water and absorbing odors that can develop in a closed system.
It helps keep the environment “sweet” by removing toxins and preventing the buildup of harmful bacteria. This is a step often skipped by novices, but it is vital for long-term ecosystem stability.
Soil and Cation Exchange Capacity
When choosing your soil mix, consider the Cation exchange capacity (CEC). This refers to the soil’s ability to hold onto essential nutrients and release them to the plants as needed.
A mix of coco coir, orchid bark, and perlite provides excellent aeration and nutrient retention. This ensures that the roots can breathe and that Pythium root rot does not take hold.
Light Requirements and Placement
Understanding light is just as important as knowing terrarium what plants to use. Most terrarium plants prefer bright, indirect light rather than direct sun.
Direct sunlight hitting a glass container acts like a magnifying glass, rapidly heating the interior. This can literally “cook” your plants and lead to a total system collapse within hours.
Artificial vs. Natural Light
If you are placing your terrarium in a dark room, a simple desktop LED grow light is a perfect solution. You can control the duration and intensity, ensuring your plants get exactly what they need.
For natural light, a north or east-facing window is usually the safest bet. These locations provide soft morning light without the harsh heat of the afternoon sun.
Avoiding Growth Issues
When plants do not get enough light, they become “leggy,” stretching their stems toward the source. This ruins the aesthetic of a compact miniature world.
Conversely, too much light can cause algae to grow on the glass. Finding the “sweet spot” is part of the fun of keeping your ecosystem healthy over time.
Recommended Plants by Growth Zone
To create a professional-looking layout, you should categorize your plants by their height and growth habit. This allows you to create a sense of perspective and scale.
| Zone | Plant Species | Benefit |
|---|---|---|
| Foreground (Low) | Sheet Moss, Cushion Moss | Creates a lush, green carpet look. |
| Mid-ground (Medium) | Fittonia, Pilea, Ferns | Adds texture and color variety. |
| Background (Tall) | Syngonium, Asparagus Fern | Provides height and a sense of enclosure. |
| Accents (Unique) | Cryptanthus, Biophytum | Serves as a focal point or conversation piece. |
How to Prepare Plants Before Planting
Before you add any foliage to your new setup, you must prepare them properly. This prevents pests and diseases from entering your clean environment.
First, gently remove the plant from its nursery pot and wash away as much of the original soil as possible. Nursery soil often contains slow-release fertilizer pellets that can cause nutrient spikes in a small terrarium.
Check the roots for any signs of mushiness or decay. Healthy roots should be firm and typically white or light brown. If you find rot, trim it away with sterilized scissors.
Finally, give the leaves a gentle rinse. This removes dust and potential hitchhikers like spider mites or aphids. Taking these steps ensures you are choosing the best species for a long-lasting display.
FAQs About Terrarium Plant Selection
Can I use garden soil for my terrarium?
It is generally not recommended to use outdoor garden soil. It is too heavy, lacks proper drainage, and often contains pests, weed seeds, and fungi that thrive in the humid conditions of a terrarium.
Why are my terrarium plants turning yellow?
Yellowing leaves are often a sign of overwatering or poor drainage. If the roots sit in water for too long, they cannot “breathe,” leading to stress and eventual rot. Check your drainage layer to ensure it isn’t flooded.
How often should I prune my terrarium plants?
Pruning depends on the growth rate of the species you chose. Generally, you should trim any leaves that are pressing against the glass, as the condensation can cause those leaves to rot and spread mold to the rest of the plant.
Can I keep carnivorous plants in a terrarium?
Yes, but they have very specific needs. Most carnivorous plants require nutrient-poor soil (like pure peat and perlite) and distilled water. They do not do well in standard tropical potting mixes.
Do I need to fertilize my terrarium plants?
Rarely. The goal in a terrarium is to keep growth slow and manageable. If the plants look pale after a year, you can use a highly diluted liquid fertilizer, but use only a fraction of the recommended dose.
Final Thoughts on Selecting Terrarium Plants
Choosing terrarium what plants to use is a rewarding process that combines art with biological science. By matching the right species to your container’s humidity and light levels, you create a sustainable piece of living decor.
Remember to prioritize slow-growing, moisture-loving plants for closed systems and drought-tolerant species for open ones. With a proper drainage layer and a bit of patience, your miniature world will flourish.
The most successful aquarists treat their terrariums like a slow-motion aquarium. Observation is key; by watching how your plants react to their environment, you can make the small adjustments needed to maintain a thriving, beautiful ecosystem.