An open terrarium is best made by layering drainage materials, adding a free-draining soil mix, and planting drought-tolerant plants such as succulents or cacti in a container with good airflow. The key is to keep moisture low, ensure proper drainage, and place the terrarium in bright, indirect light.
These miniature gardens suit a wide range of interior styles and are ideal for beginners looking for a low-maintenance introduction to indoor gardening. With the right materials and a clear process, an open terrarium can remain healthy, visually striking, and easy to care for over time.
This guide explains exactly how to make an open terrarium, from choosing the right container and plants to arranging layers correctly and maintaining long-term plant health.
• Beginner → Use a terrarium kit for the simplest setup
• Small space → Use a compact open glass container
• Succulent or cactus grower → Choose an open terrarium with strong airflow
• Decorative focus → Add sand, stones, and minimal planting
• Low maintenance → Use fewer plants and fast-draining soil
An open terrarium is a miniature garden displayed in a container without a lid or seal. The open top allows air to circulate freely, preventing moisture build-up and creating an environment that closely mimics arid and semi-arid growing conditions.
Because humidity does not become trapped, open terrariums are best suited to plants that prefer dry soil and good airflow. Cacti and succulents thrive in these conditions, while tropical plants generally do not.
Open terrariums provide ventilation and remain relatively dry, making them ideal for succulents, cacti, and other drought-tolerant plants. Closed terrariums retain moisture and warmth, which suits tropical plants such as mosses and ferns.
Choosing the correct terrarium type is essential, as placing moisture-loving plants in an open terrarium often leads to poor growth or dehydration.
Open terrariums are best for beginners growing succulents or cacti, while closed terrariums are better suited to those growing tropical plants that require consistent humidity.
Open terrariums offer several practical and aesthetic advantages:
Low maintenance: Succulents and cacti require infrequent watering and minimal upkeep.
Visual appeal: Open glass containers display plants clearly, making them attractive focal points.
Versatility: Designs can range from minimalist arrangements to decorative desert landscapes.
Educational value: Building an open terrarium provides hands-on insight into soil layering, drainage, and water management.
Creating an open terrarium for cacti and succulents involves selecting the right container, choosing suitable plants, and layering materials correctly to support healthy growth and visual appeal.
Open glass container with a wide opening
Gravel or small pebbles
Activated charcoal (recommended)
Sphagnum moss or mesh barrier
Cactus or succulent soil mix
Cacti or succulents
Spoon or small trowel
Decorative sand, stones, or gravel (optional)
Each layer in an open terrarium serves a specific purpose, helping control moisture while supporting healthy root growth.
Start by selecting a glass container with an open top, such as a bowl, vase, or geometric terrarium. The size and shape should fit your space and aesthetic preferences. A wide opening ensures adequate airflow and makes maintenance easier. Aim for a container without drainage holes so that the setup remains clean and watertight.
Choose slow-growing, drought-tolerant plants that prefer dry conditions. Suitable options include:
Echeveria
String of pearls
Bunny ear cactus
Golden barrel cactus
Avoid tropical plants or ferns, as they require higher humidity levels than an open terrarium can provide.
These plants are ideal for open terrariums because they tolerate dry conditions, require minimal watering, and are less likely to suffer from root rot in low-humidity environments.
Add a base layer of gravel or small pebbles to the container. This layer prevents water from sitting around plant roots and reduces the risk of rot.
Place a thin layer of activated charcoal above the gravel. Charcoal helps absorb impurities and keeps the terrarium fresh, especially in containers without drainage holes.
Place a thin layer of moss or mesh over the drainage materials to prevent soil from filtering downwards.
Add a free-draining cactus or succulent soil mix. Avoid standard potting compost, as it retains too much moisture. The soil layer should be deep enough to support roots without compacting them.
Remove plants gently from their nursery pots and loosen excess soil around the roots. Trim overly long roots if necessary.
Position plants in the terrarium, spacing them evenly to allow airflow and future growth. Arrange taller plants toward the back or centre, depending on the container shape.
Decorative elements such as sand, stones, or small rocks can be added to enhance the appearance and help keep moisture away from plant bases. Personalise the terrarium by adding miniature figurines, driftwood, or even seashells.
Keep decorations minimal and avoid items that may alter soil moisture or chemistry over time.
Place the terrarium in a location with bright, indirect light. Direct sunlight can overheat the container and scorch plants.
Water sparingly, only when the soil is completely dry. Overwatering is the most common cause of failure in open terrariums.
To keep an open terrarium thriving, consistent care and attention to detail are essential. Regular maintenance helps keep the miniature ecosystem healthy and vibrant.
Open terrariums perform best in bright, indirect light at room temperatures between 18°C and 24°C. Avoid placing them directly on windowsills with strong midday sun.
Succulents and cacti require infrequent watering. Allow soil to dry out fully between waterings. Signs of overwatering include yellowing leaves, while shrivelled leaves may indicate underwatering.
Ensure the terrarium remains open and unobstructed to maintain airflow. Trim dead or overgrown foliage regularly using clean scissors to prevent decay and encourage healthy growth.
Overcrowding plants
Using moisture-retentive soil
Watering too frequently
Placing terrariums in direct sunlight
Open terrariums can be customised to suit different spaces and styles:
At Miyagi Bonsai, we regularly create and maintain open terrariums using these methods, and we’ve found that simple, well-layered setups are the most reliable for long-term plant health.
Open terrariums offer a practical and visually appealing way to display plants indoors. With the right materials, careful plant selection, and minimal ongoing care, they can remain healthy and attractive for years.
By following a clear step-by-step process and avoiding common mistakes, creating an open terrarium becomes an accessible project for beginners and experienced plant enthusiasts alike.
Miyagi Bonsai stocks a carefully selected range of open terrariums, succulent plants, and essential materials, with next working day UK delivery available. If you’re unsure which setup is right for you, we can help you choose the best container and plants for your space. We are rated 5 stars across over 100 Google reviews, and our team is on hand by email and phone if you have any questions about choosing the right setup.
Common questions about making and caring for open terrariums, answered.
To make an open terrarium, you need a container without a lid for airflow, well-draining soil mix, small rocks or pebbles for drainage, activated charcoal to prevent odors, and plants suited to dry, airy conditions like succulents. Tools like tweezers and spray bottles can help maintain and water your terrarium effectively.
Succulents, cacti, and air plants are best for open terrariums as they thrive in well-aerated, dry conditions. Popular choices include jade plant (Crassula ovata), haworthia, echeveria, and tillandsia (air plants). These plants are slow-growing, drought-tolerant, and need minimal watering.
Yes, activated charcoal is recommended for open terrariums to absorb toxins and prevent odors. It also helps keep the soil fresh by filtering impurities, which is important in a contained space with limited drainage.
Drainage is crucial for open terrariums to prevent waterlogging and root rot. A layer of rocks or pebbles at the bottom improves drainage by allowing excess water to settle away from plant roots. This helps mimic natural soil conditions and supports healthy plant growth.
Regular potting soil is often too dense and retains too much water for open terrariums. Succulent or cactus mixes, which drain well, are better to prevent overwatering. Mixing sand or perlite with potting soil also improves drainage for arid-condition plants.
Watering frequency depends on plant type but generally ranges from every two weeks to once a month. Succulents and cacti prefer the soil to dry out completely between watering. Overwatering is a common mistake and can harm plants in open terrariums.
Yes, but choose plants with similar care needs, such as succulents with other drought-tolerant species. Avoid mixing moisture-loving plants with those requiring dry conditions to maintain a balanced environment.
No, air plants (Tillandsia) absorb moisture and nutrients from the air and don’t need soil. They can be placed on stones or wood inside an open terrarium and require regular misting or soaking for hydration.
Open terrariums benefit from bright, indirect light. Too much direct sunlight can overheat and dry out plants rapidly, especially succulents, causing burns. Position your terrarium in a well-lit spot without direct intense sun.
Some plants in open terrariums, like succulents, can improve indoor air quality by absorbing toxins and releasing oxygen. While not as effective as larger plant collections, they offer aesthetic and minor air-purifying benefits.
