What is a Terrarium?

A terrarium is a container designed to hold plants and animals in controlled conditions. The nature of such a system enables ‘Man’ to have complete control over the prevailing environment, stimulating anything from a desert to a rainforest.


The invention of Terrariums as we know them is credited to Dr. N.B. Ward, a 19th-century London physician, plant enthusiast.  Ward was interested in growing many types of ferns in his backyard but had not been successful. While studying a Sphinx moth emerging from a chrysalis, he buried some moist earth in a closed bottle; he was amazed to see a seedling fern and some grass growing inside. He watched them grow for four years, during which not one drop of water was added nor was the cover removed.

The defining feature of a terrarium is that it is an enclosed replica of a natural environment. Typically, the container is clear, allowing a view of the contents, although a terrarium can also be built from wood, mud and other materials.

Open Terrarium

Open Terrariums

A wide range of possibilities are available while making open terrariums but remember that open terrariums demand more attention than as compared to the closed ones.

The maintenance of an open terrarium is akin to that of maintaining a potted plant.

A clear glass container or an earthen vessel can be used. There are pro’s and con’s to each of these containers –

  1. Glass containers have absolutely no drainage pore, so one has to be a little careful while watering them.
  2. Earthen vessels on the other hand let water percolate and evaporate through their surfaces so a little extra watering does not harm to the plants.

One could choose either of these based on the preferred look and dedication one is willing to give to maintaining the terrarium.Terrarium_small

Either way there are 3 basic steps to making an open terrarium –

  1. Ensuring Drainage – The Drainage layer is the bottom most layer, consisting usually of pebbles or gravel. Followed by a layer of sphagnum moss and fine sand. The main function of this layer is to drain away excess water coming from above. The sphagnum moss is basically to disallow mixing of the sand with the gravel layer below. This is should be a minimum of one inch to a maximum of 3 inches for larger containers.
  2. Home for the Roots, The Media layer – A layer of sphagnum moss is preferred between this layer and the former sand layer just so that the media does not get mixed with one another. The best for this layer would be a potting soil mix i.e. 1/3 coco peat, 1/3 red soil and 1/3 sand. It is best not to use any kind of compost in this layer because that promotes plant growth, which may alter your layout and design with time.

It is best to fill media up to 1/3rd of the container, leaving enough room for the plants to breathe in their new home.

  1. Designing a layout and executing it – Remember to choose the plants based on light and water requirements. It is best to select plants with similar requirements since they all are going to be sharing a limited space and resources.

It is best to choose plants that don’t require high humidity to grow since most of the moisture will be lost.

One could plan out a desert layout with different succulents or slightly moist grassland with hillocks by the side! The possibilities are as wide as one could possibly imagine. With the layout planned, the plants can be laid out, taking utmost care not to disturb the root system, just like planting in a pot. Also make sure that the plant is not in contact with the glass at any side. Plants in general are not used to being in contact with another non-living object for prolong periods of time.


Plants receiving light only from one side will gradually turn towards that direction. To keep that from happening, turn the terrarium occasionally exposing different sides of the terrarium to the area with more light.

Open Terrariums usually don’t need direct sunlight, partial sunlight works best.

Make sure the soil completely dries itself out before watering.


Closed Terrariums:

A self-contained world! A closed terrarium is a controlled ecosystem which requires minimal care and attention once ready. But remember that closed terrariums require a delicate balance in order to thrive.


It is usually made of a clear glass container. The Water cycle takes place within the terrarium, so it does not require watering for months together, sometimes years.

  1. Sterilization – It is best to sterilize your container by washing with hot water and do make sure that the container is dry before you start planting.

Also sterilize the media that you plan on using. Put the media in different containers and place them all in a pressure cooker with a lot of water, and put the whistle on. Leave this on the stove for 20 minutes. This is to rid the soil of fungal spores that favor growing in damp areas.

On the other hand, if you don’t mind an occasional fungus, you could skip this step and see what takes form in your little world.

  1. Drainage – A minimum of one inch of coarse builders’ sand, gravel, or pebbles. This layer allows the excess water from above to trickle off.

This is to be followed by sphagnum moss and finely powdered charcoal. This acts as a moisture reserve and prevents any bad odor from developing. Charcoal is an extremely good adsorbent; the efficiency is based on the surface area exposed, and so make sure the charcoal is fine as dust.


  1. Growing Media – Follow the charcoal layer with Sphagnum moss to prevent the next layer mixing with the charcoal below. You can now add fertile potting soil, a minimum of one inch, but could be greater, all depending on the size of the plant you plan to put in. Make sure that this extends up to 1/3rd the size of the entire container.


There is no need to add any compost as such since potting soil contains enough nutrients for the plants.

  1. Planting – Planning before planting is a must! You could design it to be a Equatorial Rainforest or a wet grassland, create mountains out of mole hills and add other interesting stuff like bridges, ponds, huts and so on.

closed terrarium

While you get down to the real planting, make a hole in the media, tip your plant in and cover with media. It is good if you retain some of soil sticking to the roots of the plant, do not wash them all away. Tap down gently to make the roots feel like they are at home.

Make sure you keep enough space between the different plants.

One could also sprinkle a few seeds on the top most layers of growing media. This adds another dimension to your terrarium. With time the seeds may germinate and you see the changes in the ecosystem you earlier designed.

After you are done with the planting, spray the sides to clear away the extra soil. Spray water a couple more times, depending upon the size of the container. Then, close the container and check it daily for the first few days. Add a little water if the soil appears dry, and take the lid off to allow evaporation if the soil appears too moist. Once the moisture level reaches a stable state the closed terrarium will not need water for a month at the least.


Place the terrarium in a well-lit area, but never under direct sunlight, since direct sun overheats the terrarium and the plants may just get burnt in the process!

Closed terrariums recycle moisture with high efficiency, but they are more prone to disease than are open terrariums.

Common plant ailments and remedies:
1. If you find the leaves Yellowing or the leaf tips turning brown that just means there is too much moisture, try taking the top off your case for a few hours a day until plants look greener.
2. If you notice leaves falling off the plants is indicates foliage touching the glass, adjust your plants or prune the leaves in contact with the glass.
3. If you find your plants having Leggy growth that means they are not getting enough light. Place your terrarium in a well-lit area but remember not to put them under direct sunlight.
4. Brown or Black blotches on the leaves mean too much sun. Move the terrarium to a relatively dimmer area.

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