Growing A Terrarium

Tuesday, 21.06.2016

How Does Your Garden Grow? Embark on a new hobby together with your kids by building and personalising a plant terrarium to showcase at home.

With lots of imagination and creativity, terrariums are not only highly customisable, but the materials to make one are easily accessible too. Your children can have hours of fun personalising their very own miniature mobile “garden” and continue to take pride in their works-of-art with the subsequent upkeep, which is minimal yet educational.

Materials You Will Need:

  • A glass container: This can be a bowl, jar, vase or even tank, as long as the opening is large enough for little hands to go in and out without getting stuck. A lid is optional. Clear and transparent glass is best to optimally view and display the contents within.
  • An assortment of pebbles, stones, crystals: These can be of different shapes, sizes and colours for more variety and contrast. 
  • Activated charcoal: Also known as activated carbon, look for these at pet or aquarium stores, or specialty shops catered to gardening and horticulture. Activated charcoal or carbon has been treated and processed to increase its adsorption power. This therefore makes it different from the charcoal blocks used for BBQs, which are not suitable as a substitute.
  • Potting soil: This is best purchased prior from a shop, rather than scooping loose soil from an open field, which could be teeming with insects! Even better is getting soil specifically formulated for terrariums (check out your local gardening store or florist) as this has already been sterilised, is clean, and possibly pre-fertilised. Terrarium potting soil is usually a balanced mix of sand, peat soil and garden soil.
  • Plant(s) of your choice: While almost any indoor houseplant is ideal, some research is recommended before you decide. Choose plants that have similar water and light requirements. More than one plant can even be added; however, take note that some plants grow faster than others, so may require extra pruning for maintenance. Popular choices include ferns, African violets, miniature orchids and spider plants. Cacti and other succulents can also be grown, but these usually require fast-draining soil that retains very little moisture.

  • Decorative items: Choosing these is usually the most fun part of the project for children. After all, this gives them the opportunity to let their imagination run riot and even build a themed terrarium. Kids can spruce up their terrariums with plastic figurines such as favourite cartoon characters, toy dinosaurs, farm animals, cars, flags, mini dollhouses, cute and colourful erasers, seashells… the possibilities are endless. 

  • The rest: Other handy items, or tools to craft your terrarium include a scoop/spoon for transferring soil; chopsticks to position the decorative objects; gloves to keep hands clean; scissors for cutting roots or trimming leaves; spray bottle for misting the plants; as well as newspapers to line the working space and keep the area clean. 

How to Make it:

Building a terrarium is similar to baking a cake: Just imagine layering each of the required elements from the bottom upwards. Before you begin, the golden rule to remember is this: Pack each individual layer as closely together as possible! The clearly defined layers will contrast nicely and there is less risk of plant rot too. 

  1. Start filling the bottom of the container with the stones/pebbles/crystal pieces. Small containers will require a base layer that is at least 1-2 inches high; for bigger containers, the layer should be 3-4 inches deep. 
  2. Add ½-1-inch of activated charcoal on top. Charcoal or carbon will prevent algae growth and also remove toxins and odours that arise from decomposing plant matter, mould or mildew. Together, the layers of charcoal and stones serve as drainage for your terrarium. You may also choose to add another layer of live moss (an option is sphagnum moss) as extra drainage material to absorb moisture from the soil so that the plant roots will not grow damp and rot. However, unlike charcoal, moss is alive and will need occasional trimming to keep it from getting unruly.
  3. After you have placed the layer(s) of activated charcoal and moss (optional), add potting soil to the terrarium container until it is at least ¾ filled to the top. Again, make sure the soil is firmly pressed together, but not too compact as to prevent the water from reaching the roots of the plants.
  4. It’s time to add your plants! Start with the biggest first and dig out small holes in the soil where you intend to place them. Separate the roots of each plant gently so that they are not clumped together, then insert the plants one by one into each hole, before filling the gaps in with soil. Around 2-3 plants are best – don’t opt for too many as they may rapidly outgrow the container and then need frequent removal. Be sure to leave a little space between each plant to give it room to grow.
  5. Finally, add the ornaments for the finishing touch! This is the part your child gardeners are likely to find the most fun as they work towards beautifying and personalising their own envisioned landscapes.

Points to Ponder:

What can a terrarium teach kids?

Making a terrarium with your kids is a great way to teach them some responsibility about how to care for living plants and also gives them the creative freedom to make it just how they want. You can guide your kids in their observation of photosynthesis, respiration, condensation, precipitation and the water cycle that occurs within the terrarium.

In fact the water cycle is occurring all the time as the water within the terrarium is constantly being recycled. The light and heat from the sunlight evaporates the water from the plants and the soil turning it into water vapour. This condenses once it comes into contact with the walls of the container and when enough water droplets have accumulated, the condensation will precipitate down the sides of the container and return back to the soil, where it is reabsorbed by the plants’ roots. The condensation occurs even at night as a plant respires (takes in oxygen) and releases carbon dioxide and moisture back to its enclosed environment.

Open or closed terrarium?

While a terrarium functions as a mostly enclosed space, you may sometimes see the reference to “open” or “closed”. Open terrariums do not have a lid and make better environments for cacti and other desert plants as they can be placed in sunlight. The plants will need to be watered regularly however, because the enhanced air flow and brighter, hotter conditions speed up water evaporation.

Closed terrariums usually have a lid and require a lot less maintenance if left in a space with sufficient light. Plants that thrive in humid conditions are perfectly suited for a closed terrarium as the air and moisture trapped within are usually enough to sustain them for a long time. 

Maintenance and Upkeep

  • When watering your plants, it is advised not to pour water directly onto the soil. Instead, use a spray bottle to mist the plants and soil until sufficiently damp. 
  • If your terrarium is a closed one, you can minimise mould and mildew from forming by opening the lid for a few hours each day to allow air to circulate. 
  • How do you gauge if the moisture level in your terrarium is just right? If there is excess moisture, the walls of the container will become too clouded over with condensation to see properly inside. You should then remove the lid for a few hours to allow some of the water to dry out and evaporate. If there is no evidence of condensation at all, then introduce more water from the spray bottle to set things in order again. Generally, misting once a week is enough; be careful not to overwater as terrariums are, after all, enclosed containers with no drainage holes. Plants will be prone to root rot if the soil gets too damp. 
  • Terrariums thrive best under grow lights or in a space with indirect sunlight. Both open or closed terrariums should not be placed under direct sunlight to prevent the plants from overheating and avoid getting their leaves singed by the heat.
  • It’s time to trim your plants if their leaves begin pressing against the edge of the container or they begin taking up the space of the other plants. 

Remember, a terrarium is a self-sufficient ecosystem!

You will be able to observe this especially if you have opted for a closed-lid type of terrarium. The more air-tight your container is, the less frequently you will need to water the plants. More humidity = more trapped air and moisture that will continuously be recycled in the right conditions. Choose a container that is preferably made of glass and with rounded or slanted walls, so that the condensation that collects will be able to trickle back easily into the soil.

Once the plants have acclimatised to their living conditions, you might find that they require minimal care and will be able to survive – and even flourish – on their own. Get ambitious and adventurous: create more than one terrarium using a wider variety of plants. It’s truly a one-of-a-kind project that will turn out differently in different hands, and which can’t be purchased anywhere else, making it truly unique. Happy Terrarium-ing!

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