A terrarium is a miniature, self-contained garden enclosed in glass, typically featuring small plants, soil, and decorative elements. These captivating ecosystems trace their origins to the 19th century but have survived as a gardening trend into the modern era. Terrariums are adored for their ability to bring a touch of nature into homes, requiring minimal care and offering a mesmerising glimpse into the beauty of self-sustaining microcosms, making them a beloved choice for plant enthusiasts and decor aficionados alike.

The Rise of Terrariums

Terrariums have a fascinating history that dates back to the 19th century. They were originally established for scientific purposes, primarily as tools for studying and understanding plant ecosystems.

• Victorian Era: Nathaniel Bagshaw Ward, a British botanist, is credited with inventing the Wardian case in 1829, which was a sealed glass container designed to transport and cultivate plants from different regions around the world. He is also believed to have created the oldest recorded terrarium still in existence today.
  
  
• 1960s: The 1960s counterculture emphasised environmental consciousness and the return to nature. Terrariums, with their self-contained ecosystems, aligned with the desire to bring nature indoors and foster a deeper connection to the environment in a creative format.
  
  
• Present Day: With a rise in indoor plant collecting, terrariums persist in popularity due to their low maintenance and aesthetic beauty, creative possibilities, stress-relieving and meditative qualities, educational value, and sustainability. 

What is a Microclimate?

• A microclimate refers to a small, distinct climate within a larger area, with its unique temperature, humidity, and environmental conditions.
  
  
• An ecosystem, on the other hand, is a larger, interconnected community of living organisms and their physical environment.
  
  
• Terrariums create and sustain microclimates by enclosing plants and soil in glass containers.
  
  
• These enclosures trap moisture and heat, establishing a stable and controlled environment for plants, allowing them to thrive with specific climate needs regardless of the external surroundings.

Tools and Equipment

Glass container:

• Select a clear glass container with a lid (closed terrarium) or an open-top vessel (open terrarium).
  
  
• Glass containers are better than other materials as they can easily be sterilised and cleaned. Glass also retains moisture and focuses sunlight for optimal plant growth.
  
  
• Glass terrariums can be created from almost any kind of glassware. Popular choices are biscuit jars, vases, wine decanter, fish tanks, and bell jars. However, more unique ideas have included suspended light bulb casings and Christmas ornaments.

Small stones or gravel:

• Placing stones at the bottom of the container allows excess water to collect, preventing root rot by keeping the plant roots from sitting in stagnant water. As terrariums are self-contained, there is nowhere for the excess water to drain away.
  
  
• Stones and gravel leave small gaps in the soil enabling air circulation, helping to prevent mould and mildew growth.
  
  
• Stones also provide a stable base for the subsequent layers of charcoal, soil, and plants meaning the microclimate can thrive undisturbed.

Activated charcoal:

• Activated charcoal absorbs and traps odours, preventing any unpleasant smells from developing in the closed terrarium environment.
  
  
• It helps maintain a sterile and healthy environment by absorbing excess moisture and inhibiting the growth of mould and harmful bacteria.
  
  
• Charcoal acts as a natural filter, purifying water that may collect in the terrarium's lower layers and ensuring that it remains clean and free from contaminants.

Potting soil:

• For a terrarium, you'll want to use a specific type of potting soil that promotes proper drainage and moisture retention.
  
  
• A suitable choice is a high-quality, well-draining potting mix, like "cactus mix" or "succulent mix." These soil mixes typically contain ingredients like sand or perlite for better water retention and improved drainage.
  
  
• Avoid using standard potting soil, as it retains too much moisture, which can lead to root rot in the enclosed environment of a terrarium.

Other tools:

• Long tweezers or chopsticks: These are vital for precise plant placement in terrariums' small openings, minimising contamination risk and aiding maintenance. They reach tight spaces, ensuring a healthy and attractive miniature ecosystem.
  
  
• Add decorative elements: Visually appealing rocks, pebbles, moss, miniature figurines, or decorative sand for aesthetics.
  
  
• Small watering can or misting bottle: Watering and humidity maintenance. 

Plant Selection

Several plants thrive in terrariums due to their adaptability to enclosed environments, slow growth, and small size.

• Succulents (e.g., Haworthia, Echeveria): Succulents are drought-resistant and compact, making them ideal for open terrariums. They require minimal water and add a unique texture to your miniature garden.
  
  
• Air Plants (Tillandsia): Air plants don't need soil, absorbing nutrients and moisture from the air. They come in various shapes and sizes, adding an intriguing element to your open terrarium.
  
  
• Ferns (e.g., Maidenhair Fern, Miniature Boston Fern): Ferns thrive in high humidity and low light conditions, making them well-suited for closed terrariums. 
  
  
• Miniature Orchids (e.g., Mini Phalaenopsis): These small orchids adapt to the confined space and add delicate, exotic beauty to your terrarium, requiring minimal maintenance.
  
  
• Moss (e.g., Sheet Moss, Pillow Moss): Mosses are excellent ground covers that thrive in terrariums' moist conditions. They create a lush carpet and complement other plants while aiding in moisture regulation for open and closed terrariums.
  
  
• Fittonia (Nerve Plant): Known for its vibrant, variegated leaves, Fittonia adds a pop of colour and thrives in the humid environment of a closed terrarium.
  
  
• Pilea (Aluminum Plant): Pilea's compact size and attractive foliage make it a great choice for terrariums. It's easy to maintain and adds visual interest.
  
  
• Peperomia: With its unique leaf shapes and adaptability to low light, Peperomia is another versatile choice for open or closed terrariums.
  
  
• Tropical Bromeliads: Miniature Bromeliads, such as Neoregalia, can thrive in the high humidity and warmth of a terrarium, providing a striking focal point.
  
  
• Begonia: Some miniature begonia varieties are well-suited to terrariums, offering attractive leaves and occasional blooms.
  
  
• Ficus Pumila (Creeping Fig): This trailing plant can be trained to grow upright, resembling a miniature tree, and is suitable for larger open terrariums.
  

• The Pot Belly (Bunyan Fig): is an attractive and resilient indoor plant and suits terrariums perfectly by storing moisture in their trunks. However, be mindful that this is a tree and the roots can grow quite large.

Creating a Terrarium

• Start with a layer of small stones or gravel to aid drainage.
• Add a layer of activated charcoal to prevent mould and odours.
• Top with potting soil, ensuring a depth suitable for your plant’s roots.
• Use your long tweezers to dig small holes in the soil layer. Place the plant's roots into the hole, and gently pat the soil around the base to secure it.
• Leave some space between plants to allow for growth and airflow.
• Once all plants are in place, you can add decorative elements like pebbles or moss to cover the soil surface for an aesthetically pleasing finish.
• Evenly water in the plants in an open terrarium container until the topsoil is moist.
• Only lightly water the soil if it feels dry to the touch before sealing a close-lid container. A closed-lid terrarium should retain the right amounts of moisture from the soil and plants without needing additional moisture.
• Condensation on the glass means that the plants are absorbing and transpiring water as they should. This condensation will drip down and water the plants over time, creating a self-sustaining ecosystem.
• Do not wipe away the initial condensation as you are removing vital water needed to kick-start the microclimate. 
• Place your terrarium in indirect sunlight. Avoid direct sunlight to prevent overheating.

Problems and Solutions

• Decreased condensation: Only water the terrarium when you notice a significant decrease in condensation or when the plants appear to be brittle or pale in colour. Use a small watering can or misting bottle to lightly spray the top soil to restore moisture.
  
  
• Excessive condensation: If you notice persistent condensation in a closed-lid terrarium, it may be too humid. Leave the lid slightly ajar for a few days to allow excess moisture to escape and restore a balanced humidity level. You can also gently wipe the inside of the container or soak up excess water with a small piece of paper towel wrapped around your tweezers for precision.
  
  
• Mould or algae growth: Excess moisture can lead to mould or algae in closed-lid terrariums. To address this, open the lid for a while to allow the terrarium to dry out. Remove any affected plant material, and ensure proper airflow to prevent future mould growth.
  
  
• Wilting or yellowing leaves: Wilting or yellowing leaves may result from overwatering or inadequate drainage. Adjust your watering routine, ensuring the soil isn't waterlogged. Prune dead or yellowing foliage to promote plant health.
  
  
• Pest infestations: Occasionally, pests like aphids or mealybugs may infest terrariums. Isolate the affected plant and remove the pests manually, or use a gentle insecticidal soap. Quarantine new plants before adding them to your terrarium to prevent introducing pests.
  
  
• Soil compaction: Over time, the soil in your terrarium may become compacted, limiting airflow to the roots. Gently aerate the soil by pocking small holes into it with a small stick or fork, being careful not to damage the plants' roots.
  
  
• Plant overgrowth: Some plants may outgrow the terrarium over time. Prune or trim them as needed to maintain a balanced and visually appealing environment.
  
  
• Fertilisation: Over time, the nutrient levels in the soil can become depleted, especially if the terrarium has been established for a while. If you notice reduced plant growth or signs of nutrient deficiency you can introduce a significantly diluted liquid fertiliser that is about a quarter of the recommended strength advised on the packaging.

Terrariums offer a mesmerising glimpse into the world of miniaturised nature. Crafting your own terrarium garden can be a rewarding and creative endeavour, offering a unique blend of gardening and artistic expression. With the right container, plants, and care, your homemade terrarium can thrive and become a conversation piece in your home. So, let your imagination run wild and build your own little world inside a glass jar!