Horticulture Magazine

How To Make A Terrarium In 5 Simple Steps

mini succulents in a glass terrarium on a windowsill

Terrariums have been popular for well over a hundred years, and it’s easy to see why.

These gorgeous, compact gardens are fascinating to observe from week to week and make a fabulous living ornament for your home.

Terrariums reward you with gorgeous plants with little time and effort, as well as providing a unique insight into how they grow.

Through the glass, you can observe the journey of the roots through the layers of soil, making it a great learning opportunity for adults and kids alike.

So, whether you have limited space, limited time, or simply want an ultra-low maintenance gardening experience – terrariums are the answer.

And, while you could buy one at your local garden centre, they are super easy and fun to make, and we are going to show you how.

What is a terrarium?

Terrariums are small, encased environments where certain plants can grow.

They are essentially mini-greenhouses and are typically made from transparent containers made from glass or plastic.

a terrarium jar with its own ecosystem
Trending in the Victorian era, terrariums are still popular today.

Terrariums were actually invented by accident by one Nathaniel Bagshaw Ward in 1842. [source]

Ward had an interest in observing insect behaviour and accidentally forgot about one of his many jars.

Inside a fern spore grew, germinated into a plant and thus the first terrarium was created, although back then it was known as a Wardian case. [source]

The Victorian public was enamoured with this novel, glass-encased garden, and the trend soon took off. [source]

It’s safe to say they’ve stood the test of time: terrariums are still popular to this day.

How to make a terrarium

As you’d expect, open terrariums are just as easy to make as the sealed ones, and here’s how to do it:

What you will need:

equipment needed to build a terrarium, all laid out on a wooden table
  • A glass or plastic container – no lid required for this one!
  • Cactus potting compost
  • Activated charcoal
  • Your selection of plants
  • Long-handled spoon
  • Long tweezers
  • Aquatic gravel (you can buy this in pet shops)
  • Gardening gloves if you are handling spiky plants
  • Decorative materials such as moss and rocks if you wish

Now that you have everything you need, it’s time to get started. Here are the steps to create your very own open terrarium:

1) Add Compost To Your Container

using a hand trowel to scoop compost into terrarium glass in bulb shape

Spoon your potting compost into the container and sprinkle a thin layer of active charcoal on top.

2) Dig A Hole For Your Plants

hand using a small wooden spoon to dig a hole in terrarium soil

Using the spoon dig a small hole that allows adequate space for your chosen plants.

3) Add Your Plants

succulent being moved into glass terrarium with bowl in background

Remove the plants from the pots, use gardening gloves if required, and gently massage the roots to loosen them from the soil.

4) Firm Up The Soil

firming up the soil with a wooden spoon

Place the plants in the hole and use the spoon to gently firm the soil around them to make sure they are securely in place.

5) Add Aquatic Gravel

aquatic gravel being added the terrarium surface soil

Add a layer of aquatic gravel. We do not recommend using decorative gravel as this will not provide sufficient levels of drainage.

finishing shot with all gravel added

Top tip: If you find the plants in either style terrarium are covered in soil when you are finished, use a small paintbrush to gently brush the debris away.

completed terrarium sat on wooden table

How do terrariums work?

There are two types of terrarium: sealed and open. Sealed ones have a removable lid while the open ones do not.

Sealed terrariums

a sealed glass terrarium sat on an indoor shelf

Sealed terrariums are pretty much self-sufficient.

The temperature in the terrarium will be higher than room temperature, meaning the plants and soil will produce moisture.

The moisture then evaporates and condenses on the side of the container, before trickling back down to the soil.

This cycle will repeat, essentially recycling the water indefinitely.

Being transparent, the container will also allow for photosynthesis to occur.

Terrariums are therefore self-nourishing so require very little care and maintenance.

Open terrariums

succulents in multiple glass terrariums
Terrariums mean you can design your own desert!

As you would expect, open terrariums do not require a lid, and often the plants will grow up and out of their container.

Unlike sealed terrariums, open ones create drier conditions instead of a moist environment.

As they are exposed to open-air, these terrariums don’t have a regular water cycle so require watering frequently, usually once a week or when the soil becomes dry, and you notice leaves falling from plants.

Desert plants are ideal for open terrariums as they don’t require humidity and need access to more oxygen and humidity to thrive.

Best plants for terrariums

Creating terrariums is exciting, but perhaps the most crucial decision before you begin is choosing the right plants for your new pint-sized garden.

Where sealed terrariums are concerned, you are going to want to pick small, slow-growing foliage plants such as ferns, carnivorous plants and tropical plants that thrive in humidity.

different plants being placed into a fishbowl terrarium, including multiple types of succulents

You basically get to create your own, personal, tiny rainforest!

As mentioned open terrariums generate dry conditions so you’ll want to include slow-growing air plants, cacti and succulents.

With open terrariums, you can build your miniature dream desert.

Caring for your terrarium

Part of the joy of terrariums is they require very little attention; however, there are a few things you can do to ensure they stay healthy and last for as long as possible.

  • If you are growing ferns, you can trim them occasionally to prevent them from outgrowing their little home.
  • Keep an eye out for and remove yellowing or brown leaves as this can be a sign of pests and disease.
  • With closed terrariums, you can occasionally take the lid off to allow it to get some fresh air.
  • With open terrariums, do weekly checks to see if you have any visible pests such as gnats or mealy bugs.
  • Sealed terrariums can be watered once a month, although it will depend on the plants you have chosen to include.
  • Open terrariums benefit from being watered every 3-6 weeks.
lightbulb terrarium hanging with lights and photographs in the background

Dealing with pests

If you begin having problems with pests, then we recommend using insecticidal soap on the infected plant.

However, if this doesn’t solve the problem quickly, it is best to remove the plant altogether to prevent further spread.

You can then replace it with a fresh, new healthy plant.

Top tip: Always check your plants before buying to make sure there are no pests or signs of disease.

Treat yourself and build your own terrific terrarium

As you can see, terrariums are a breeze to make and make such attractive decor for your home.

Once you’ve made your own, you can simply place it in a sunny spot and enjoy it.

They also make wonderfully unique gifts and are a great way to upcycle and repurpose old jars, vases other household items.

Two terrarium jars with plants inside
Terrariums make superb gifts!

Terrariums also give you the opportunity to grow plants you couldn’t ordinarily grow in your garden and are so rewarding for keen gardeners who just don’t have enough time or ample space to do traditional gardening.

Being so fun to make, and such low maintenance, terrariums can also provide a fantastic opportunity for children to learn about how plants and their ecosystems work.

So, if you are ready to reinvent the rainforest or redesign the deserts, then treat yourself and build your very own, terrific terrarium.

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