---
title: Closed vs open terrarium | Glass Jar Garden
description: A closed terrarium keeps its own water and stays near 95 to 100% humidity; an open one dries out and needs watering. Which to build, and the 15 plants that only suit one.
url: https://glassjar.garden/guide/closed-vs-open-terrarium/
---

Guide

# Closed vs open terrarium

A closed terrarium keeps its own water: plants breathe it out, it beads on the glass and runs back to the soil. An open one loses water to the room and needs watering, but suits plants that rot in still, wet air.

Closed (sealed)OpenAir insideNear 95 to 100% humidityClose to the roomWateringRarely: the water goes roundRegularly: about 0.1 cm a day of wet surface at 20 °C, more when warmSuitsFerns, moss, tropical plantsSucculents, air plants, anything that rots in damp airWatch forGlass fogged all day: too wet, open it a whileDrying out between wateringsPlants that only suit it8 of 497 of 49

## How the simulator treats the lid

- Sealed: water goes round, out of leaves, onto the glass, back to the soil.
- Sealed air sits near 95 to 100% humidity.
- Open: water evaporates, faster when warm, dry or wide-mouthed.
- Venting lets some humidity and water out of a sealed jar.
- Glass fogs on cool mornings; fogged all day means too wet.

- Open evaporation: 0.1 cm a day of wet surface at 20 °C

- Per °C warmer: 7% more

- Lid gasket leak: 0.02 air changes an hour

## Plants for a closed jar only

These need the steady humid air of a sealed jar and struggle open.

- [Jewel orchid](https://glassjar.garden/guide/plants/ludisia-discolor/), easy
- [Krauss's spikemoss](https://glassjar.garden/guide/plants/selaginella-kraussiana/), easy
- [Peacock spikemoss](https://glassjar.garden/guide/plants/selaginella-uncinata/), easy
- [Flask-shaped pitcher plant](https://glassjar.garden/guide/plants/nepenthes-ampullaria/), moderate
- [Rex begonia (miniature cultivars)](https://glassjar.garden/guide/plants/begonia-rex-mini/), moderate
- [Shingle plant](https://glassjar.garden/guide/plants/marcgravia-rectiflora/), moderate
- [Maidenhair fern](https://glassjar.garden/guide/plants/adiantum-raddianum/), demanding
- [Tailed orchid (miniature Masdevallia)](https://glassjar.garden/guide/plants/masdevallia-mini/), demanding

## Plants for an open jar only

These rot or sulk in a sealed jar's still, wet air.

- [Haworthia](https://glassjar.garden/guide/plants/haworthia/), beginner
- [Air plant](https://glassjar.garden/guide/plants/tillandsia-ionantha/), easy
- [Burro's tail](https://glassjar.garden/guide/plants/sedum-morganianum/), easy
- [Button fern](https://glassjar.garden/guide/plants/pellaea-rotundifolia/), easy
- [Echeveria](https://glassjar.garden/guide/plants/echeveria/), easy
- [Jade plant](https://glassjar.garden/guide/plants/crassula-ovata/), easy
- [Venus flytrap](https://glassjar.garden/guide/plants/dionaea-muscipula/), moderate

The rest, 34 plants, are fine either way. [The best plants for a closed terrarium](https://glassjar.garden/guide/best-plants-for-closed-terrarium/) lists every one that lives sealed.

[Try both in the simulator](https://glassjar.garden/)

## More terrarium guides

- [Best plants for a closed terrarium: Plants that live sealed, easiest first.](https://glassjar.garden/guide/best-plants-for-closed-terrarium/)
- [Best moss for a terrarium: Mosses for closed and open jars, and what they grow on.](https://glassjar.garden/guide/best-moss-for-terrarium/)
- [Terrarium layers explained: Drainage, barrier, soil and top dressing, and what each does.](https://glassjar.garden/guide/terrarium-layers/)
- [Terrarium drainage: LECA vs gravel vs lava rock: Every drainage material side by side.](https://glassjar.garden/guide/drainage-leca-vs-gravel/)
- [Mould in a terrarium: Why new jars fuzz, which mould matters, and how to stop it.](https://glassjar.garden/guide/terrarium-mould/)
- [Springtails vs isopods: The cleanup crew compared: what each eats and where it lives.](https://glassjar.garden/guide/springtails-vs-isopods/)