How to Set Up a Bioactive Terrarium (Step-by-Step Guide)

A well-designed bioactive terrarium doesn’t just look good—it also makes life easier for you and healthier for your animals. Instead of constantly spot-cleaning a bare enclosure, you create a small ecosystem with plants, microfauna and a living soil layer that helps process waste over time.

In this guide, I’ll walk you through the basic steps of setting up a bioactive terrarium, using the same approach I use when I build and test mixes for Indoor Biosphere.

What Is a Bioactive Terrarium?

A bioactive terrarium is an enclosure that includes:
• A living soil or substrate layer
• Leaf litter and/or botanicals
• A “clean up crew” of microfauna (usually isopods and springtails)
• Live plants that help use nutrients and stabilize the environment

The goal isn’t to eliminate all maintenance, but to create a more natural, self-stabilizing system that supports both your animals and the small organisms living in the substrate.

Step 1: Choose the Enclosure and Plan the Layout

Before you think about substrate, decide what kind of enclosure you’re building:

• Approximate size (5 gallon, 10–20 gallon, 30–55 gallon, tall arboreal, etc.)
• Species and number of animals you plan to keep
• Whether the enclosure will be more horizontal (terrestrial) or vertical (arboreal)

Have a rough idea of where you want hides, climbing areas, plants and open space. This will help you place cork bark, background pieces and planting pockets later.

Step 2: Add a Drainage Layer (If Needed)

Many bioactive builds use a drainage layer underneath the main substrate. This helps prevent water from pooling around roots and keeps the soil from becoming waterlogged.

Common options include:
• Lightweight clay balls or similar drainage media
• A layer of coarse gravel or rock at the bottom

If you use a drainage layer, separate it from the substrate with a mesh or screen so the soil doesn’t sift down and fill the gaps. Not every enclosure requires a drainage layer, but it is very helpful in taller or heavily planted, humid setups.

Step 3: Add the Bioactive Substrate

The substrate is the foundation of the whole system. It needs to support plant roots, hold moisture without staying soggy, and provide a habitat for isopods, springtails and other microfauna.

A typical bioactive mix includes some combination of:
• A base component (such as heat-treated cocoa coir or similar material)
• Structure and aeration (orchid bark, small pieces of wood, or similar)
• Organic matter (worm castings, composted material)
• Clean leaf litter, plant trimmings and root cuttings

In my shop, this is where mixes like “Best Soil on Earth” come in—they’re blended specifically for planted vivariums and clean up crews. For most enclosures, aim for a substrate depth that allows you to plant securely and gives animals room to burrow where appropriate.

Step 4: Add Sphagnum Moss and Leaf Litter

Once the main substrate layer is in place, it’s time to add texture and cover.

• Sphagnum moss can be used in pockets, around plant bases, or in higher-humidity zones to help hold moisture and protect roots.
• Leaf litter creates a natural forest floor. It gives isopods and springtails places to hide and feed, and it slowly breaks down into the soil over time.

Use clean, appropriate hardwood leaf litter that has been processed to reduce pests. Spread a layer over much of the substrate, leaving some open areas where needed.

Step 5: Hardscape – Cork Bark and Natural Features

Hardscape gives your terrarium structure and character. Cork bark flats and other natural pieces can be used to create:

• Hides and shelters
• Climbing surfaces
• Backgrounds and ledges
• Visual focal points

Place your cork bark before planting, so you can see where shadows will fall and where animals are likely to spend their time. Make sure any climbing pieces are stable and secure.

Step 6: Plant the Terrarium

Choose plants that match your animal’s environment and the conditions inside the enclosure. Good terrarium plants are usually:

• Small to medium-sized
• Humidity-tolerant
• Comfortable in moderate to low light

Examples include nerve plants (Fittonia), small pothos, creeping groundcovers and other tropical species. Plant taller or bushier plants toward the back or sides, and use low-growing species in the foreground.

After planting, gently firm the substrate around the roots and water lightly to help them settle.

Step 7: Add the Clean Up Crew (Isopods & Springtails)

Once your substrate, leaf litter and plants are in place and the enclosure has been lightly watered, it’s time to introduce your clean up crew.

Isopods and springtails will:
• Break down decaying leaves and waste
• Help aerate the substrate
• Contribute to a more balanced micro-ecosystem

Add them directly to the leaf litter and substrate. Give them time to settle in before heavily disturbing the enclosure. Over the next few weeks, they’ll begin to establish and reproduce if conditions are right.

Step 8: Let the System Settle

Before you add animals, it’s usually best to let the bioactive system run for a bit on its own. This gives time for:

• Plants to recover from transplanting
• Microfauna to settle and start breeding
• Moisture levels and temperature to stabilize

Use this period to adjust lighting, ventilation and watering until the enclosure feels stable and consistent.

Step 9: Ongoing Care and Maintenance

A bioactive terrarium reduces some types of maintenance, but it doesn’t eliminate all work. Plan to:

• Check moisture levels and water as needed
• Trim plants that outgrow the space
• Refresh leaf litter periodically as it breaks down
• Spot-clean larger messes or uneaten food as appropriate for your animals

The payoff is a more natural-looking enclosure that supports healthier behavior and is often easier to manage long-term.

Bringing It All Together

Setting up a bioactive terrarium is about building a small, balanced ecosystem: substrate, leaf litter, plants and microfauna, all working together around your animals. Once the basic layers are in place, each enclosure becomes its own little world.

If you’re not sure which substrate, leaf litter or clean up crew is right for your specific setup, feel free to reach out. I’m always happy to help you choose the right combination of materials for your enclosure size and the animals you keep.