Animals, Charlotte O, Container Gardening, Gardening, How To, Planters, Plants

Build Your Own Closed Terrarium

If you don’t have your own small animal audience, store-bought is fine.

Exciting news folks! Primrose has recently got in a whole new selection of terrarium making tools, the first on the site made specifically for closed-system terrariums! Well since they’re so new, and terrariums are finally making the come back they deserve, I went and wrote up the journey through creating my own closed-system terrarium.

You will need

All of this and a good dash of patience.

The sets we have online also include a very handy shovel and rake set that extends to reach the bottom of your jar, these are indispensable if you have a very deep terrarium! (Although you could always wrap some wire around a fork and a spoon, no judgement here.)

If possible, it’s recommended to find a piece of plastic mesh to help keep the stone and soil layer separate, but don’t worry if you can’t get hold of any, I didn’t use it in my terrarium.

Also handy:

  • A lot of newspaper to work on (it gets messy!)
  • A funnel (I made one out of a cereal packet)
  • Scissors (for pruning if needed)
  • Small hand trowel (for removing soil from roots)

And last but not least, the plants and accessories you want in the terrarium.

These are the two species I used, Tradescantia Purple Passion at the front and a Chlorophytum Comosum behind.

The process

The idea of a closed terrarium is to create an ecosystem that will sustain itself. Both the plants and soil release moisture that becomes water vapour, and condenses against the walls of the terrarium during the warm daylight, falling back to the soil in the cooler evenings. This creation of an enclosed watering system is what will keep your terrarium growing, but just throwing dirt and plants at it isn’t going to work, an irrigation system is needed to stop the soil from rotting under too much water.

At this point you’ll want to grab the funnel, or if you’re on a budget, make one out of cardboard or paper to make for easier application of the materials.

First pour in a layer of small stones, pebbles, or gravel. There’s no hard and fast measurement as it depends on what size receptacle you’re using, a good rule to stick to is one-quarter stones to three-quarters soil. Remember this layer has to be deep enough to stop any pooling water from sitting in the soil.

I’d highly recommend checking out this video on youtube for a visual representation: https://www.youtube.com/watch?v=7Lg4tzkHgVo

Check your terrarium from all angles, sometimes it’s hard to judge the level of coverage with curved glass.

Next is activated charcoal. This is an integral ingredient in the tasty soup that is your closed terrarium. It absorbs chemicals in the soil, water, and air that could otherwise build up over time and damage the plants. Charcoal also cleans up unpleasant odours that are released from the decomposing soil and helps stop mildew forming.

You don’t need a whole layer of the stuff, but make sure there’s a good handful being placed in, it’s going to do a lot of work after all!

If you’ve been able to source some plastic mesh, now is the time to cut it to shape, fold it up and pop it in. You’ll need some long tools to push and pull it into place, and then you can add the substrate. (Note that the charcoal seems fine both above and below the mesh layer.) Again, if you don’t have a mesh layer don’t worry! You can still power on!

Okay, let’s layer up some soil! You’ll need a decent amount, remember we’re working to approx one-quarter stones to three-quarters substrate. Don’t worry if your measurements aren’t perfect, it’s all a learning process!

Make some small divots for the plants to sit in, and let’s move on to prepping some plants!

Easy as 1, 2, 3!

Plant choices

A closed terrarium is a specific type of environment. There’s a lot of damp warmth in there, and if left in direct sunlight, the refraction of the glass will cook everything inside. So we need moisture-loving, low light-thriving, quite small plants. Which admittedly cuts down our options somewhat, but here are some plants that I’ve discovered-

Small ferns will help fill out any space, and they’re relatively easy to come by. Try and find a miniature variety if you can, as some ferns can grow pretty big.

Some that come recommended:

Peperomia, Maidenhair fern, Pteris, and Adiantum. I chose a variegated fern to place in mine, the pot I purchased had three separate plants in it so I picked out the smallest to place in my also quite small terrarium.

Soleirolia variants are perfect as well, and have a variety of amusing names such as, mind-your-own-business, baby’s tears, angel’s tears, friendship plant and Irish moss. (It is in fact, not a moss, but a plant from the nettle family.)

Tradescantia- also known as Spiderwort, is another plant that does well in humid climates. There are a lot of variants though, and I’d recommend staying away from any that are flowering as they will wilt and die quickly in the terrarium. I chose a Tradescantia Purple Passion to place in mine.

Other tropical foliage such as Dizygotheca and Neoregelia ‘fireball’ enjoy a humid environment, making them other possibilities for your display.

To finish it off I would recommend some moss. I took a trowel and dug some out of my garden. Moss is a great way to fill out your terrarium, it helps to cover bare soil and brings more diversity into the jar.

Trixie spent the whole time trying to eat my plants and the moss. Thanks Trix.

Preparing plants

This section entirely depends on what container you’re using for your terrarium, but for brevity’s sake I’m going to assume you’re using the same line of terrariums that I am, and in that case you’ve got some trimming to do. The opening of the bottle is a lot smaller than you first think, so you’ll need to carefully extract the plants from their pots, and gently scrape or shake off most of the soil around the roots so you can fit it through the top. This is where having another container or a lot of newspaper down comes in handy to catch all the soil!

Move the plant around after it’s fallen inside, and make sure you push soil back around the roots when you’ve confirmed the placement.

Now is a good time to consider the layout of your terrarium. Instagram and Pinterest are great sources of inspiration, just make sure whatever you use is small enough to fit!

In my terrarium I used some old chunky sticks to create a divide in the middle, putting the fern one side and the tradescantia on the other, with moss liberally applied all around. To finish it off, I added some more height with a mossy stick reaching up through the bottle, remember to consider your layers to make for a more visually interesting display!

Here’s my finished terrarium! I’m very pleased with how it turned out, and it didn’t take more than about half an hour to put together!

Finishing off

Before adding the cork, make sure you give your terrarium a good spritz with a spray bottle, or pour a little water down the side. You don’t need to add the cork straight away – allow the bottle to stand for a day to let the plants settle, and for the first week or so, take the cork off for a few hours every day. This allows you to adjust the water, and allows the plants to breathe and accumulate to their new closed-system environment a little easier.

Keep your terrarium out of direct sunlight, and rotate it every day or so to allow all sides to soak up some heat.

And here’s my beauty after 2 weeks! The tiny wild clover in the moss are loving it!

Troubleshooting and the future

There’s always the fear that your terrarium won’t last the weekend. Fear not! If you’ve used the right plants and followed the guide you should be safe. One thing to bear in mind is the water cycle, moisture should build up over the day, then drip back down to the soil overnight. If there is too much condensation then plants might start to rot, so remove the cork and allow it to dry out a little. If there’s no moisture on the sides by late afternoon, it may need a spritz of water to keep the cycle going.

If it does unfortunately go wrong, there’s no shame in calling it a day, dumping it all out and starting again. We all have to start somewhere, and I’m sure your next terrarium will look amazing!

If you do make up one of our terrariums, be sure to snap a photo and send it in!

Bonus points for getting your pets involved!

 

Charlotte at PrimroseCharlotte is a Copy Writer at Primrose, writing product descriptions and about anything else that comes her way. She owns 2 rabbits and 5 chickens that she loves very much. (Her garden is most certainly not tidy).

When not at her desk you can find her attempting to find her way back to Japan again, or drawing.

See all of Charlotte’s posts.

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