How to Build a Bioactive Terrarium That Looks Beautiful and Takes Care of Itself

Bioactive terrariums are more than just a pretty display—they’re living, self-sustaining worlds in miniature.

What sets them apart from simple planted terrariums is the addition of tiny inhabitants. “Detritivores, in our case, isopods and springtails, are added in," says Rae Serfilippi, an ecological restorationist, of the small anthropods. "This more closely mimics what happens in our forests and fields."

Besides being fascinating to watch, these ecosystems invite us to slow down, connect with nature, and develop a deeper appreciation for the outside world. Best of all, once they’re established, bioactive terrariums are surprisingly low-maintenance.

What You'll Need

A thriving bioactive terrarium starts with the right materials. Make sure to gather them thoughtfully and sustainably.

Choose a Container

“For bioactive terrariums, there are many size options, mostly determined by which type of isopod is being kept,” Serfilippi says.

She recommends starting with at least a half-gallon container, but in her workshops, she uses one-gallon cookie jars to give powder isopods extra room to roam. Thrift shops and flea markets can be treasure troves for unique glassware.

Select the Plants

Many tropical plants flourish in terrarium conditions.

“Start with smaller plants that grow slowly or take to pruning well so they don't outgrow their environment too quickly,” says Serfilippi. Overplanting early isn’t a problem—in fact, some isopods may even enjoy nibbling on the fresh foliage.

Source Your Moss Ethically

Sourcing live moss is rarely as simple as heading to your local nursery and purchasing it. Moss has particular growing conditions, so you'll either need to order it through a well-vetted specialist, or ethically harvest it yourself.

“Never take from forest systems where it's playing a vital role in the ecosystem,” says Serfilippi. Moss growing on pavement, in sidewalk cracks, or along building foundations is fair game, however—as long as it’s free from fertilizer or pesticides.

A good rule of thumb to follow: If it’s living happily among other plants, leave it there.

Recruit Your Clean-Up Crew: Isopods and Springtails

“Isopods are the nutrient cyclers in these closed systems and allow them to continue to thrive for years, or even decades,” says Serfilippi. "Springtails manage mold and fungi to keep the terrarium clean."

Whether sourcing from local breeders or online, choose species that match your terrarium’s climate—tropical or arid—and container size. Larger isopods will require more space to roam.

Source Your Layers

Think of your terrarium like a layer cake. You’ll need:

• Leca (lightweight clay aggregate)
• Dried leaves
• Potting soil
• Soil amendments: horticultural charcoal, perlite, tree bark, peat, and earthworm castings

How to Make a Bioactive Terrarium

Time to put it all together. Sourcing the right plants and isopods will ensure this step is successful.

Add Your Drainage Layer

“Every terrarium I build starts with a drainage layer of leca, or fluvum, at the bottom. It provides space between the bottom of the glass and the plant roots to prevent rot,” Serfilippi says.

It also acts as a water gauge—if you see standing water there, then you’ve gone a little overboard on your watering, and will want to pull back.

Create a Barrier

Skip the mesh. Serfilippi prefers dried oak leaf litter to create a barrier between the drainage and soil layers. This doubles as food and habitat for isopods, while also keeping things tidy.

Add Soil

Next, add a chunky, nutrient-rich soil mix of charcoal, flaked bark, peat, perlite or vermiculite, and earthworm castings. Serfilippi recommends mixing in crushed leaf litter for extra organic matter. 

"Always keep in mind how tall your plants are and how deep they need to be seated into the soil so that there's enough room at the top of the jar,” she says.

Add Plants and Décor

Time to do a little landscaping. Nestle your plants into the soil, covering the roots completely, and work in your larger hardscaping pieces, which will act as both a food source and shelter for your isopods. 

“Adding in chunks of baked hardwood or cork bark is always beneficial, as our isopods appreciate having it to munch on and use as habitat,” Serfilippi says. Place moss mainly around the edges against the glass, where condensation will keep it moist.

Introduce Your Clean-Up Crew

Once plants and décor are in place, it’s time for the stars of the show to take the stage: your isopods and springtails.

How to Care for Your Terrarium

Bioactive terrariums will mostly take care of themselves, but you still want to keep an eye on them.

Water

“Bioactive terrariums need a little more care up front, but quickly become self-sufficient," Serfilippi says.

Early on, you’ll water more frequently and deeply to kick-start the ecosystem—about once a week, until condensation appears consistently, and until  the surface layer of soil and moss are saturated. 

After that, you may only need to water monthly. If water pools in the drainage layer, remove the lid for a few hours to let it evaporate.

Light

Aim for bright, indirect light—ideally four to six hours daily. Near a sunny windowsill (but not in direct, harsh rays) works best. You could also supplement your terrarium with grow lights if you don't have good natural light.

Food

While the leaf litter feeds your isopods, they’ll appreciate occasional treats. “Fish food pellets are a great source of protein and can be dusted with isopod powder,” Serfilippi says.

Calcium, which helps baby isopods develop strong exoskeletons, can come from crushed eggshells, and small portions of veggie scraps can be occasionally offered as well—but only in amounts they can finish before spoilage.