Which plants for a closed geometric terrarium?
A geometric terrarium that closes takes tropical plants, never cacti. The plants that suit by glass height, how to place them in three layers, and those to avoid.
In this guide
A geometric terrarium that closes takes tropical plants: plants that like humid air and soft light, and that stay small. It takes no cacti and no succulents.
This rule is surprising, because many photos show succulents in faceted glass. Those photos show open models. So first check whether your terrarium closes.
Open or closed: the question that decides
- Open geometric terrarium: the air circulates, the soil dries quickly. This is the realm of succulents and cacti. See our guide to the succulent terrarium.
- Closed geometric terrarium: the water evaporates, settles on the glass and falls back. The air stays humid. This is the realm of tropical plants.
Our terrariums in the Prisme collection close with a removable glass panel. This whole guide is about that case.
The plants that suit
| Plant | Its place | What it brings |
|---|---|---|
| Fittonia | At ground level | Colour: leaves veined in white, pink, red or orange |
| Fern | In the centre | Relief, fine foliage |
| Calathea | In the centre | Broad, patterned leaves |
| Coffee plant | In the centre or at height | Glossy green foliage |
| Mini palm | At height | The vertical line |
| Asparagus | In the centre | Light foliage, almost a mist |
| Ginseng ficus bonsai | Alone, as the centrepiece | A tree in miniature |
| Living moss | Everywhere at ground level | The hills, the deep green |
For each plant, our guides go further: fittonia, fern, calathea, bonsai.
The height of the glass chooses the plants
A plant must fit under the glass, with room to grow. Measure the height of the terrarium first.
Low glass, 17.5 cm: the carpet
A long, low glass is planted like a carpet. Fittonias measure about 10 cm, pot included: they fit. Living moss fills the gaps. The Prisme Mosaic kit follows this idea: five fittonias in five colours, between cushions of moss.
Medium glass, 23 to 29 cm: the jungle in three layers
This is the height that allows a true landscape.
- At the top: a mini palm or a coffee plant.
- In the centre: a calathea or a fern.
- At ground level: two fittonias and living moss.
The Prisme Jungle kit follows this plan, with six plants in a glass of 28 × 26 × 24 cm.
Tall glass, 36 cm: the tree
A ginseng ficus bonsai needs at least 25 cm under the glass. So it needs a tall terrarium. You plant it in the centre, and place the other plants around it, lower, so that it stays the main piece.
Composing: three florist's rules
- One star only. A bonsai, a palm or a carpet of colour. Not all three.
- From top to bottom. The tall plant at the back or in the centre, the low ones in front. In a terrarium seen from every side, the tall plant goes in the centre.
- Room to grow. Leave a few centimetres between the plants and the glass. A leaf pressed against the glass stays wet and gets damaged.
The plants to avoid
- Cacti and succulents: they rot in humid air.
- Aromatic herbs: they need sun and air.
- Fast-growing plants: they touch the glass within a few weeks.
- Potted flowering plants: the faded flower goes mouldy under the glass.
After planting
For the first weeks, mist forms on the glass in the morning. This is normal: the terrarium is finding its balance. Our guide to condensation explains when to open it.
After that, the tasks are few.
- Bright light, without direct sun.
- Watering once or twice a year.
- Glass panel removed for a few hours, once a month.
- A trim when a plant touches the glass: see pruning a terrarium.
In short
- A terrarium that closes: tropical plants, never cacti.
- The height of the glass chooses the plants.
- Three layers: top, centre, ground.
- Living moss to finish the landscape.
To choose the glass, read our guide to the geometric terrarium.
Sources
- Creating a Closed Terrarium, Penn State Extension
- How to Design a Closed-System Terrarium, Mississippi State University Extension
- Manufacturer data sheets for the terrariums (dimensions, materials, manufacture, lead time)
- DIY bottle terrariums make great projects, gifts, University of Illinois Extension
Frequently asked questions
Can you put succulents in a geometric terrarium?
In an open model, yes. In a model that closes, no: the air stays humid there, and succulents and cacti rot. A closed terrarium takes tropical plants.
How many plants in a geometric terrarium?
Three plants in a small glass 16 cm long. Five or six in a glass of 27 to 50 cm. Add living moss to cover the soil.
Which plant for a low terrarium?
Fittonia. It is about 10 cm tall, pot included, and it comes in white, pink, red, orange and bright green. With living moss, it makes a carpet of colour.
Do you need to water a closed geometric terrarium often?
No. Once or twice a year. Also remove the glass panel for a few hours, once a month, to change the air.
