Outdoor Terrarium: How to build and maintain one

You love terrariums but don't know if you can put them outside? So did I, until I found out that not all terrariums are suitable for outdoors. In this post, I want to show you how to create and maintain a beautiful outdoor terrarium. I'll explain which plants are super suitable for an outdoor terrarium and all the things you need to consider. An outdoor terrarium is a great way to add some greenery and beauty to your garden, balcony or patio. Here are the most important things you should know about them:

  • What are outdoor terrariums?
  • What are the advantages of outdoor terrariums?
  • What are the challenges of outdoor terrariums?
  • How do you build and maintain them?

What are outdoor terrariums?

A terrarium is a small ecosystem in a glass container that usually contains tropical or subtropical plants. A terrarium is basically a miniature greenhouse that creates a humid and warm climate for the plants. It can be closed or open, depending on how much air exchange and watering the plants need.

A glass terrarium with succulents and cacti, outside.
A closed terrarium with succulents in the sun

An outdoor terrarium is nothing more than a terrarium that is suitable for outdoor use. This means that it contains plants that are adapted to the local climate and can withstand temperature fluctuations and weather conditions. An outdoor terrarium can also be an open container filled with soil, which in principle works no differently than a normal flower pot.

Some well suited plants for an outside terrarium are:

  • Succulents and cacti: These plants are very low maintenance and require little water. They can grow in both closed and open containers.
  • Herbs and grasses: These plants are ideal for open containers, as they need plenty of sun and air. Some can even be used as spices or teas. Plus, they're perfect for filling empty spaces in your terrarium.
  • Small trees and shrubs: Bonsais, for example, are perfect for large containers that offer plenty of space. Not only can they create a nice contrast to the small plants in the terrarium, but they can also be great eye-catchers.

For more, check out this article: The Ultimate Guide to Terrarium Plants.

Here are some pictures of outdoor terrariums that can inspire you:

A large rectangular terrarium with a bonsai tree, moss and ferns inside. The terrarium is placed on a wooden table in a garden with flowers and grass. The photo was taken around noon on a sunny day with bright daylight.
A large bonsai in a rectangular terrarium outside
A glass terrarium with succulents and cacti in a desert theme on a wooden bench.
An open terrarium with succulents and cacti outside

What are the advantages of outdoor terrariums?

Outdoor terrariums have many advantages over other planters or indoor terrariums. Here are some of them:

Low maintenance: Outdoor terrariums need little water and fertilizer. Open terrariums are watered by rain and visited by insects, which fertilize your plants virtually for free, all due to being outside. Closed terrariums don't have that luxury, but create their own microclimate that can last like forever. You only need to check them from time to time and water them when the soil is dry.

Great for upcycling: Outdoor terrariums are a great way to get creative and save the environment at the same time. You can use old glass jars that you would otherwise throw away, or ones that you find cheap at flea markets or online. You can then fill these containers with plants that require little water and fertilizer, such as succulents or cacti. In this way, you not only save water, but also money. You can also grow several plants in one container and save space. You don't even have to buy new plants, you can just take cuttings from plants you already have at home. This way you can create your own little ecosystem and beautify your garden or balcony.

Decorative: Outdoor terrariums are not only beautiful to look at, but also a great addition to your outdoor space. They can add more color and life to your garden, balcony or patio. In addition, they can serve as gifts or souvenirs and are again a much more beautiful eye-catcher than just a single potted plant.

Three outdoor terrariums with different shapes and plants on a wooden table in a garden.
Three different options for outdoor terrariums

What are the challenges of outdoor terrariums?

Weather conditions: Weather can greatly affect outdoor terrariums. Extreme temperatures can stress or burn the plants. This is especially a problem with closed terrariums due to the greenhouse effect. Wind can break the glass or blow away the substrate if the glass is open.

Rain can flood an open terrarium or drown the plants. For these reasons, you should place your terrariums in a sheltered location and bring them indoors during inclement weather. You can also use a thermometer or humidity meter to monitor conditions in the terrarium.

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In a best-case scenario, you can even use a smart thermometer with an app to take action as quickly as possible during extreme weather outside.

Pests: Pests such as snails, ants or spiders can nest in outdoor terrariums. They can attack the plants or spread diseases. Slugs can eat holes in the leaves or leave unsightly slime trails. Ants can loosen the soil or attract other insects. Spiders can spin webs or bite the plants. You may want to let nature take its course and make your terrarium look wild. If not, you can use natural remedies like coffee grounds, cinnamon or vinegar to keep pests away.

Diseases: Problems such as mold, rot or fungus can also occur during fluctuating weather. They can cause plants to die, making the terrarium an unsightly mess. Mold can form on the glass or substrate and degrade the air quality. Rot can destroy the roots or stems of the plants and cause an unpleasant odor, and fungi can stunt the growth of the plants or even be toxic. You can prevent all this the better your terrarium is ventilated and the looser the soil is. You can read more about fungi and mold in this article: Why does mold grow in a closed terrarium?

The soil police can help you out here! Meaning detritus eaters that remove your rotten plants. Read more here: Why woodlice are important for a closed terrarium.

Woodlouse closed terrarium
A woodlouse on a tree bark. Source: piqsels.com

How do you build and maintain outdoor terrariums?

An outdoor terrarium is a beautiful and easy way to keep plants outside in your garden. To create your own outdoor terrarium, all you need are a few materials and some creativity. Here are the steps you should follow:

The container and drainage

Choose a suitable container. You can recycle an old glass jar or buy a new one. Make sure it's large enough to hold your plants and has an opening to let in air and water. Above all, the jar should be sturdy so that it doesn't break immediately if the wind ever blows a little harder. If you have an old aquarium at home, this is perfect. This is because the glass is particularly stable.

Fill the bottom with a drainage layer of gravel or puffed clay. This layer prevents too much water from accumulating in the terrarium and rotting the roots of the plants. The layer should fill about a quarter of the vessel. You can also add some sand to improve drainage. It is even better if you place a thin fly screen over the drainage layer before adding the soil on top. This will prevent the soil from being washed away by the water.

A false bottom in a closed terrarium
A false bottom in a closed terrarium

Activated carbon cleaning and soil layer

Add some activated carbon. This layer helps to clean the water in the terrarium and prevent unpleasant odors. The layer should be about one centimeter thick. You can find the activated carbon in a garden or pet supply store. Instead of a layer, you can also mix the activated carbon into the potting soil.

Add the potting soil. The soil is probably the most important thing for your plants. It provides them with nutrients such as nitrogen, phosphorus and potassium. It also gives them support and stability. The layer should fill about half of the container, so that the plants have enough space to spread their roots. You can use a special soil for terrariums, adapted for the needs of terrarium plants. Or you can mix a regular potting soil with some peat or perlite to improve drainage and aeration.

The plants and a protective layer of moss

Plant your chosen plants. You can combine different plants that have similar needs. For example, you can use succulents, cacti, grasses or herbs. Make sure you leave enough space between the plants to give them room to grow. You can also dig some holes in the soil to insert the roots of the plants.

A sunny garden scene with three potted plants on a wooden table. A prickly cactus, a lush fern and a fuzzy grass.
Three different plants for a terrarium.

Add a layer of moss or bark. This layer protects the soil from drying out and gives the terrarium a more natural look. The layer should completely cover the soil. You can also add some ferns or small flowers to make the terrarium more lively.

Final touches

Add some decorations, such as stones, shells, figurines, etc. These elements can add more personality and charm to the terrarium. Be careful not to use too many decorations so as not to clutter the terrarium. You can also choose some themes, like fairy tale, jungle or beach.

Sprinkle the terrarium lightly with water. The water should slightly moisten the soil, but not soak. The water will help the plants adapt to the new environment. You should only water the terrarium when the soil is really dry.

If you are building an enclosed terrarium and are unsure how much water to use, read this article here: How much water does a closed terrarium need?

Place the terrarium in a suitable place outdoors. The terrarium should get a bright and protected place, not exposed to direct sunlight or strong wind. You can put the terrarium on a table or bench. If it is not so big, you could also hang it on a hook.

Closed terrarium hanging from a rope
A closed terrarium hangs on a rope

More tips for the care of an outdoor terrarium

To prevent or control pests or diseases, you should check the terrarium often and keep it clean. This includes removing withered or dead plant matter and using natural remedies such as vinegar or soapy water when you discover pests or diseases. While you can let nature take its course, algae will quickly form on the glass, which may not look very nice.

Learn more about how you can clean a terrarium here: Tips and tricks for cleaning a closed terrarium.

Green algae in a closed terrarium
Green algae and other dirt

Watering the terrarium is an important factor for the well-being of the plants if there has been no rain for a long time. You should only water the terrarium when the soil is very dry to avoid waterlogging. It is best to use a spray bottle or watering can with a thin spout to distribute the water evenly. Only add as much water as the terrarium can hold without it collecting at the bottom.

The terrarium is also sensitive to extreme temperatures or strong winds. You should not expose the terrarium to temperatures below 0°C (32°F) or above 35°C (95°F), as these can damage the plants. If it gets too cold or too hot, move the terrarium indoors or to a sheltered area. If it gets too windy, place the terrarium in a sheltered area and, if necessary, put something heavy on the lid to keep it from blowing away.


As you can see, outdoor terrariums are a great way to beautify and green your outdoor space. They're not hard to make and maintain if you follow a few simple rules. Once again, here are the top tips for your outdoor terrariums:

  • Select plants that are adapted to the local climate and can withstand temperature fluctuations and weather conditions.
  • Choose a appropriate container that has an opening and is large enough to hold your plants.
  • Fill the vessel with different layers of drainage, activated charcoal, soil and moss or bark.
  • Add some decorations to give the terrarium more personality and charm.
  • Spray the terrarium lightly with water and place it in a bright and sheltered outdoor location.
  • Check the terrarium regularly for pests or diseases and water only when necessary.
  • Protect the terrarium from extreme temperatures or strong winds and move it indoors or to a sheltered area if necessary.

Now it's your turn. Have you ever kept a terrarium outside? How did it turn out for you? Do you have any other tips or questions about the topic? Drop me a comment or share this post with your friends who also love terrariums.

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