So just what is a terrarium, anyways?

Simply put, a terrarium is a tiny ecosystem filled with various types of plants enclosed in a container, usually made of glass or plastic. That makes them sound a bit boring, though – they can be as imaginative as you can make them! It all depends on your creativity and how much time you’re willing to put into getting the various elements just right.


An open terrarium with plants in a glass container.

A small open-style terrarium

For the absolute basics of a terrarium, you need a glass container, some pea gravel, some soil, and some plants. The bottom of the container is lined with the gravel and then layered over with soil, where you then grow your plants (of course). After planting your seeds or transplanting your chosen terrarium plants, you carefully water the soil. Here is the point where two schools of thought develop: closed-style and open-style.

Closed terrariums try to act as completely self-contained ecosystems. Once the container is closed and the terrarium is placed in the sun, a miniature version of the water cycle is established as water evaporates from the soil and condenses in the “sky”, which is really the inside of the glass container, where it then “rains” back down the sides of the glass into the soil. This is such an effective process that a carefully constructed closed-style terrarium can function without any adjustments for over 40 years!

This terrarium has been unopened for 40 years!

The fabled 40 year old terrarium!

Open terrariums obviously require a lot more maintenance – at least when you compare them to the closed style. The more open your terrarium is, the more you’ll have to water it to keep everything properly hydrated; a bottle garden wouldn’t need as much watering as an open-topped aquarium case.

This draws us to the point that the style of container you choose can make a huge difference in how successful your project is, what types of environment you can create, and how difficult they are to actually construct. For a basic starter terrarium planted from seeds, you can try using a clear glass or plastic bottle, or if you want to transplant larger plants into your terrarium, start with a more open-mouthed container such as a glass jar or empty aquarium. As you get more familiar with the processes and pitfalls of building your own terrariums, or if you’re just feeling adventurous, consider trying out some more exotic containers. Take ten dollars to your local dollar store and buy a few different glass containers with unique shapes. They don’t have to be glass or even intended as actual containers – repurposing items is a great way to find something truly unique.

Many people try to create a natural style of environment in their terrariums, trying to replicate a particular ecosystem: a miniature forest glade, a pool in a bog or even a desert oasis. These are all great options, and we cover some diy terrarium ideas for different ecosystems on other pages of the site, but a more unique option is to go for something a little more avant garde (if anything about a terrarium could ever be avant garde). Let your imagine start to run away with you. This style of project is going to be much harder to build and pull off, but with the right terrarium supplies, you just might be able to pull it off. Consider the project from a design perspective, but open your mind to the possibilities of using non-plant elements in your terrarium, maybe only using one or two carefully-chosen plants as highlight/accent pieces in the middle of something more akin to a zen garden? If you can imagine it, you can build it!

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