Terrarium FAQs

Terrariums are tiny, self-contained ecosystems. They are designed to be low maintenance, slow growing, and long-lasting — but they do behave very differently to houseplants. With the right placement and a light-touch approach, your terrarium can thrive for years. If you’re ever unsure, you’re always welcome to reach out.

What kind of terrarium do I have?

Most of our terrariums are closed or semi-closed systems, created for moisture-loving plants such as mosses and ferns. If your terrarium has a cork, lid, or stopper, it is considered closed. If it has no lid and remains permanently open, it is an open terrarium. Closed terrariums recycle moisture internally, which is why their care differs so greatly from traditional potted plants.

How the terrarium water and air cycle works

A closed terrarium functions as a self-contained ecosystem that continuously recycles its own water and air. Once established, this internal cycle allows the terrarium to sustain itself with very little intervention.

Moisture naturally evaporates from the soil and plants, rises within the terrarium, and condenses against the glass as tiny droplets. These droplets then fall back into the soil, re-watering the plants and restarting the cycle. This process repeats again and again, often for months at a time, without the need for added water.

Condensation is a visible sign that this cycle is working. Light condensation, particularly in the morning that clears slightly throughout the day, indicates a healthy balance. If there is no condensation at all for several days, the terrarium may need a very small amount of water. If condensation is heavy and constant, with water dripping down the glass or the soil appearing soggy, there is too much moisture in the system.

Air is also continuously recycled. During the day, plants release oxygen through photosynthesis. At night, they respire, taking in oxygen and releasing carbon dioxide. Microorganisms within the soil help maintain this balance, creating a stable internal environment. Keeping the terrarium closed most of the time allows both the water and air cycles to regulate naturally.

Opening the terrarium too often disrupts this balance. For this reason, the lid should only be removed briefly to release excess moisture or to address a visible issue. When left undisturbed, the ecosystem will usually correct minor imbalances on its own.

Do I need to water my terrarium?

In most cases, no. Closed terrariums recycle their own moisture and rarely require watering. Only consider adding water if there has been no condensation at all for several days, the soil appears completely dry, and the plants look limp or dull. When in doubt, it is always better to wait. Overwatering is the most common cause of terrarium failure.

How much water should I add if it needs it?

Very little. Small terrariums typically need five to ten sprays from a mist bottle. Medium terrariums require one to two teaspoons of water, and large terrariums no more than one to two tablespoons. Water should always be added slowly, then observed over the next 24 to 48 hours. There should never be standing water at the bottom of the terrarium.

Is condensation normal?

Yes. Condensation is not a problem — it is part of a healthy terrarium cycle. Light condensation that appears and clears naturally is ideal. Persistent heavy condensation, dripping glass, or soggy soil indicates excess moisture. If this occurs, simply remove the lid for one to three hours, then replace it.

Where should I place my terrarium?

Terrariums prefer bright, indirect light. A well-lit room or a position near a window is ideal, as long as the terrarium is protected from direct sunlight. Direct sun can quickly overheat the glass and damage the plants. Terrariums should also be kept away from heaters, fireplaces, and heat pumps.

What temperature is best?

Terrariums thrive in stable indoor temperatures, ideally between 15 and 25°C. Avoid placing them near heat sources, drafts, or areas with frequent temperature fluctuations.

How fast do terrarium plants grow?

Terrarium plants grow slowly by design. These ecosystems are intended to remain compact and balanced. Over time, plants may change shape, shift, or grow at different rates as the system matures. This is normal and expected.

Do I need to trim or prune my terrarium?

Occasional gentle trimming may be needed if a plant begins touching the glass or overcrowding the space. Use clean scissors and remove trimmed pieces from the terrarium. Avoid pulling plants out by the roots unless something has clearly failed.

I see mould — is my terrarium dying?

Not necessarily. Small amounts of white mould can appear, particularly in newer terrariums. This is usually resolved by increasing airflow. Opening the terrarium for a few hours and removing any visibly affected material with tweezers is often enough. If mould persists or spreads, please get in touch for guidance.

Are bugs normal?

Tiny soil organisms may occasionally appear and are often beneficial to the ecosystem. If you notice larger insects or a sudden infestation, contact us for advice. This is uncommon and usually fixable.

What should I avoid doing?

Avoid overwatering, placing your terrarium in direct sunlight, opening the lid frequently, moving it often, or treating it like a houseplant. Terrariums thrive when they are left largely undisturbed.

Why terrariums sometimes fail (and how to avoid it)

Most terrarium issues are caused by too much care rather than neglect. Overwatering is the most common problem, as terrariums do not dry out like houseplants. Direct sunlight can quickly overheat the ecosystem, while frequent opening disrupts the internal balance of moisture and air.

Treating a terrarium like a regular pot plant, or expecting it to look exactly the same over time, can also lead to disappointment. Terrariums are living systems and naturally evolve. Ignoring early warning signs such as heavy condensation, soggy soil, strong smells, or sudden plant collapse can allow small issues to become larger ones. Gentle, early adjustments make all the difference.

How long should my terrarium last?

With proper care, a terrarium can last for years. They are not disposable décor but living ecosystems that gradually change over time. Some variation in appearance is natural and healthy.

My terrarium doesn’t look like it did on day one — is that okay?

Yes. Terrariums mature and rebalance themselves. Changes in growth, condensation patterns, and plant positioning are part of a healthy system. Perfection isn’t the goal — life is.

Still unsure?

If something doesn’t feel right or you’d like reassurance, please reach out. We’re always happy to help you understand what your terrarium is doing and how to support it.