A terrarium is a glass vessel where plants grow, protected from cold and draughts. Whether the vessel is sealed or unsealed, it provides an indoor microclimate and space for a beautiful enclosed garden.

Even if you don’t have any outdoor space of your own, a terrarium will connect you to nature and plants. And looking at living plants is another way of reducing stress, so we’re all in favour. Having a terrarium has been pretty trendy for a few years now, and making one yourself is even better.

Choose your vessel

Your vessel should be clear transparent glass. For beginners, it’s best if you can get your hand through the opening because then it’s easier to work. You could use a fish tank, a fish bowl, a mixing bowl, a Kilner jar, a jam jar – anything glass.

A small vessel might only hold one plant, or a slighter bigger one just two or three.

DIY closed terrarium.

DIY closed terrarium. © Kitty Terwolbeck and reused under https://creativecommons.org/licenses/by/2.0/

Choose your plants

Think about where you will situate your terrarium because this will affect the plants you put in it.

An open vessel is best for a sunny windowsill, with plants such as succulents or perhaps carnivorous plants like the Venus flytrap. Being open will keep it free from too much moisture which rots plants, and will prevent too much heat building up which kills plants.

An open terrarium with succulents and cacti.

An open terrarium with succulents and cacti. © Sonny Abesamis and reused under https://creativecommons.org/licenses/by/2.0/

A closed vessel has a moist environment and is good for a location with lower light levels. Ferns, moss, ivy and bromeliads will all do well here. For larger vessels, Alys Fowler suggests the missionary plant (Pilea peperomioides), golden pothos vine (Epipremnum pinnatum) and tradescantia species (spiderworts). She also suggests buying 3cm plants online.

How to make your terrarium

  1. Spread some pea gravel 3-4cm/2in thick in your glass vessel. Some people use larger pebbles.
  2. Put a layer of moss over the gravel to keep the compost moist and to prevent it from seeping into the gravel. Lawn moss works well here.
  3. A layer of charcoal helps to keep smells sweet.
  4. Then layer at least 4cm/2in of potting compost, or more depending on the type and size of your plants.
  5. Plant carefully into the compost and tamp it down around the plants.
  6. Water or mist sparingly.

Aftercare

Plants in a sealed terrarium will provide enough oxygen, carbon dioxide and moisture to keep themselves alive. Keep an eye on the terrarium for a few months to make sure it’s not too moist. If you see condensation on the glass or fungus on the plants or soil, remove the lid to allow some of the moisture to escape. Then replace the lid and continue to monitor the situation. A balance will be reached and afterwards it will need hardly any care.

An open vessel requires more water and care, as moisture is lost to evaporation.

More advice from terrarium maker Ken Marten here.

Or you could have a soil-free terrarium

And for this, you need air plants which thrive in any vessel you fancy.

Hanging globe terrarium for air plants

Hanging glass globe terrarium for air plants. © Cherus and reused under https://creativecommons.org/licenses/by-sa/3.0/

Unwind a little by watching plants grow in a terrarium.