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Creating a closed terrarium in 6 steps

Nothing quite as trendy as an enclosed terrarium or bottle garden, an ecosystem in a bottle with mini plants. And in 6 easy steps you can make your own terrarium.

Closed terrarium or bottle garden

Bottle gardens were all the hype in the 1960s and 1970s and are all the way back. Not surprisingly, they are very decorative and require little or no care. The only condition is that you give the plants a good start.

Once you have decorated the bottle, humidity and temperature remain fairly constant and the plants are also protected from outside pollution. The closed terrarium thus forms its own mini-ecosystem.

closed terrarium 4

What you need for your terrarium

  1. a perfectly clean bottle that can be properly sealed with a stopper made of glass, cork or metal
  2. small pebbles, cobbles, gravel or decorative stones for plants
  3. active carbon (in the pet store at aquarium supplies) or crumbled charcoal
  4. potting soil for indoor plants
  5. a sheet of moss
  6. mini plants, preferably species that like a humid environment and thrive at a temperature between 16 and 25° C
  7. possibly a funnel, plastic tube, scoop and fork (e.g., disposable cutlery)

closed terrarium


Here’s how to make your own mini-ecosystem

1. Rinse gravel, pebbles or stones clean under running water, drain well and dry completely. Put a layer of pebbles ± 3 cm thick on the bottom of the bottle. This is the drainage layer that prevents the plants from standing in the water with their roots. To keep the inside of the bottle clean you can put a tube to the bottom and let the pebbles slide down through it.

2. Place a circle of carbon or charcoal in the center of the drainage layer. This will keep the soil clean and the plants healthy.

3. Then apply a thick layer (± 5 cm) of potting soil. Use the tube for this as well or do it with your hands if the neck of the bottle is large enough.

4. Remove the mini plants from the plastic pots and gently shake off the dry, loose soil.  Place the plants in the layer of potting soil in the bottle.  Start with the smallest plant and finish with the largest. Press the soil firmly all around.

5. Finally, place a layer of moss on the potting soil around the plants and pour some rainwater into the bottle.

6. Place the bottle in the chosen location and leave it open for at least a week.  Then put the stopper halfway up the bottle opening for a week.  Then close the bottle. If too much condensation forms, you can open the bottle occasionally for a day. In time, this will no longer be necessary.

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Additional tips for creating an enclosed terrarium

  • Don’t put too many plants in the bottle (2 to 3 usually suffice) and don’t plant them too close together either.
  • Plants that don’t grow too fast and don’t get too big are best suited.
  • For your first terrarium, choose a bottle with a neck opening that your hand can pass through.
  • For a terrarium for plants with a narrow neck opening you will need additional tools. With disposable cutlery glued firmly to a bamboo stick, you can make plant holes in the potting soil and guide the plants as well. With a cork or a very small wood block glued to a stick you can compact the potting soil.
  • Do not place the enclosed terrarium in direct sunlight; glass can intensify sunlight so the plants have an increased risk of burning.

Tip> read our Top 10 easy indoor plants

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How much water in plants terrarium?

In an open terrarium, this is very different than in a closed terrarium. This is because you only pour water in once before you close it and let the plants do their thing. It is best to use some rainwater. Make sure you have the perfect balance and do not use too much, but certainly not too little water.

How does a plant terrarium work?

Thanks to photosynthesis, the plants release water in gaseous form (water vapor). The water vapor condenses against the glass wall, after which the water droplets roll downwards. … Because the glass of a closed terrarium is sealed with a cork, for example, we create a mini-ecosystem.

closed terrarium 3

What charcoal for terrarium?

Therefore, provide a small amount of active carbon, crumbled charcoal or hydro pellets. They keep the soil in your terrarium clean and thus your plants healthy. You will find (active) carbon or hydro grains in your garden center
This is a great project to tackle, isn’t it? You can make it as big or as hard as you want. Personally, I do think this is one of the best birthday gifts to give a close friend. Also because it needs so little care!


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