Essential Tips for Creating a Successful Terrarium at Home

One of the things I enjoy most is getting someone else onto the terrarium bandwagon. I truly believe this is one of the best hobbies you can have. You work with your hands, reconnect with nature, explore your creativity, and touch on science through experimentation. Terrariums bring a living slice of nature indoors, creating tiny ecosystems that thrive inside glass containers.

This AI image was too funny not to share… If only assembling terrariums were as easy as phasing your hands through the glass.

These miniature gardens offer a wonderful way to enjoy plants without needing a large outdoor space. Yet many beginners struggle to keep their first handmade terrariums healthy and vibrant. In this guide, I share practical advice drawn from my own experience to help you master the world of terrariums and cultivate a thriving green ecosystem right on your windowsill.

Choosing the Right Container

The container sets the stage for your terrarium’s success. Glass containers are ideal because they allow light to reach the plants and help maintain humidity. You can use anything from a simple jar to a decorative glass bowl or a specialised terrarium case.

There are surprisingly few containers sold specifically as “terrarium containers”, and when you do find them, they are often very expensive. I am constantly scanning every shop I walk into to see whether they might have something that could become the next home for a living art creation.

Let’s look at the main types of containers.

Open Containers

When you search online, you’ll often read that open containers are best suited for plants that prefer drier air, such as succulents and cacti. While that isn’t wrong, I personally love open containers for most plants. If a plant is sold in your area as a houseplant, I can almost guarantee it will do well in an open terrarium.

The main difference is maintenance. Open terrariums need occasional watering, as moisture escapes more easily. With a little attention, they are incredibly versatile and rewarding.

Closed Containers

Closed containers create a humid environment that is ideal for tropical plants such as ferns and mosses. The absolute magic of a closed terrarium is that you can create a fully functional ecosystem that never needs to be opened again.

Watching the natural water cycle unfold inside these containers is truly amazing. Condensation forms, water returns to the soil, plants grow, leaves decay, and nutrients are recycled naturally.

When choosing a closed container, pay close attention to the lid. Wooden lids must be properly sealed to prevent moisture loss and rot over time. Glass lids are always the safest and most reliable option.

Before planting, always clean your container thoroughly to prevent mould and bacterial growth. I wash each container with very hot water and soap, then rinse it again without soap and let it air-dry completely before starting to build the ecosystem.

Selecting Suitable Plants

Choosing plants with similar light, water, and humidity requirements is essential. Mixing incompatible plants almost always leads to stress and failure.

I also like to think about both short-term beauty and long-term growth. Sometimes I add a faster-growing or less expensive plant alongside a slower-growing “feature” plant. This way, the terrarium looks full and beautiful from day one, while the primary plant slowly establishes itself and eventually takes over.

Plants for Closed Terrariums

Closed terrariums work best with tropical plants such as fittonia, small ferns, and mosses. The goal is to create a stable ecosystem that requires no intervention. Some of my closed terrariums have been sealed for over seven years without ever being opened.

Choose plants that tolerate constant humidity and don’t require their leaves to dry out completely. Small ferns are ideal, as they naturally fill the space and recycle their own fallen leaves into nutrients.

Avoid plants that rot easily or need airflow around their leaves.

Plants for Open Terrariums

Succulents and air plants are commonly recommended for open terrariums because they prefer lower humidity. That said, I also absolutely love using orchids in open terrariums.

Most orchids dislike constantly wet leaves, which makes closed terrariums unsuitable for them. Open containers — especially bottles with smaller openings — create the perfect balance of humidity and airflow. These containers retain moisture while still allowing air exchange.

Building terrariums through narrow openings is more challenging, but that challenge is part of the fun. A good pair of long tweezers, like those used in aquascaping, is essential.

Avoid large or fast-growing plants that will quickly outgrow the container. Remember: you are planting for the next years, not just the next few weeks. In terrariums, less is almost always more.

Preparing the Base Layers

A terrarium’s foundation plays a critical role in managing moisture and keeping plants healthy.

1. Drainage layer:

   Start with a layer of pebbles or gravel to prevent water from sitting around plant roots. I prefer larger pebbles because they look better and make the water level easy to see.

   
   

   I often mix in LECA (Light Expanded Clay Aggregate), commonly used in hydroponics. It levels nicely and adds visual interest. Make sure to rinse all drainage materials thoroughly before adding them — otherwise, you’ll end up with cloudy water.

   
   

2. Divider/Mesh layer:

   This layer is essential to prevent soil from leaking into the drainage layer.

   I use a double-layer approach:

   • Bonsai drainage mesh for structure and flexibility

   • Weed barrier fabric on top of the mesh

   Weed barrier fabric is a soft black material used in landscaping. It allows air and water to pass through while keeping soil firmly in place, perfect for terrariums.

   
   

3. Filter layer:

   1. Activated charcoal: Absorbs toxins, odours, and impurities while reducing mould and bacterial growth.

   2. Sand: Acts as a natural filter and barrier, helping prevent root rot and mimicking natural soil layers.

      
      

4. Optional Sphagnum moss layer:

   This can help prevent soil from mixing into lower layers. Because I already use weed barrier fabric, I often skip this layer, especially in smaller containers. I haven’t noticed any difference in success either way.

   
   

5. Substrate layer aka the soil:

   The soil mix depends on your plant type and container:

   • Cactus mix with added sand for succulents

   • Peat-based soil with perlite for tropical plants

   • Peat, sphagnum moss, vermiculite, and perlite for ferns and orchids

   
   

This layered setup mimics nature and creates a stable, healthy environment.

Planting and Arrangement Tips

This is where creativity really takes over.

My basic approach:

• Visualise how each plant will grow over time

• Place taller plants toward the back or centre

• Use smaller plants and ground covers near the front

• Add moss from your garden — it almost always works beautifully

• Leave space for airflow and growth

  
  

Use tweezers or chopsticks to position plants carefully without disturbing roots. After planting, lightly mist with a spray bottle to settle the soil and clean any dirt off the leaves.

Lighting Requirements

Light is one of the most important, and most experimental, aspects of terrarium care.

Even identical containers can behave very differently depending on placement. Too much direct sunlight can literally cook your plants inside glass. It’s far better to start with slightly too little light than too much.

• Place terrariums near bright, indirect light

• North- or east-facing windows work well

• Avoid direct afternoon sun

• If natural light is insufficient, use grow lights for about 12 hours a day

  
  

For closed terrariums, I look for morning condensation followed by clear glass as the day progresses — a sign of a healthy water cycle.For open terrariums, I check substrate moisture late in the morning. It should feel slightly moist, never soggy or bone dry.

If you notice algae growing in the drainage water, it’s usually a sign of too much light. Algae is almost unavoidable, but it only becomes a problem when exposed to excessive sunlight.

Watering Practices

Watering terrariums is all about balance.

Unlike potted plants, minerals don’t flush out of a terrarium. For this reason, always use distilled or reverse-osmosis water to prevent mineral buildup.

• Closed terrariums: Rarely need watering. I keep the water level at about half the height of the drainage layer.

• Open terrariums: Need more frequent watering, but only small amounts. Never exceed the drainage layer.

  
  

Use a spray bottle or small watering tool, and adjust based on plant response. Yellowing leaves or mould are signs that watering needs correction.

Maintaining Humidity and Airflow

Humidity levels vary depending on the terrarium type and plants.

• Closed terrariums naturally maintain high humidity

• Open terrariums may benefit from occasional misting, especially ferns

• Good airflow reduces fungal issues

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If your base layers are done correctly, mould is rare. I’ve personally never had mould issues in a well-built terrarium.

Expanding Your Terrarium Skills

Once you’re comfortable, experiment. Try different plant combinations, container shapes, and decorative elements. Create themed terrariums, desert landscapes, rainforest scenes, or miniature forests.

Each terrarium becomes a unique piece of living art, evolving over time and telling its own story.