Closed vs Open Terrariums: What’s the Difference?

If you’ve ever stared at a terrarium for a bit too long, you’ll notice they don’t all behave the same way. Some look misty and almost fogged up, like they’ve got their own little weather system going on. Others feel dry, clean, a bit more minimal.

That’s not just aesthetic. That’s the difference between closed and open terrariums.

And honestly, choosing between them isn’t about what looks nicer. It’s more about how much effort you want to put in, and what kind of plants you like keeping around. This guide gets to the bottom of that.

What Is a Terrarium?

At the simplest level, a terrarium is just plants in a glass container.

But the glass changes things. It holds in moisture (or doesn’t), traps heat (sometimes a bit too well), and creates a small environment that behaves differently from your usual potted plant.

So once you put plants inside glass, you’re not just “decorating”. You’re kind of setting up a system. A small one, but one that governs its own little microclimate.

Closed Terrariums

Closed terrariums are the ones that look like they’re sealed off. Maybe there’s a lid, or the opening is small enough that air doesn’t really move in and out. Inside, moisture is constantly contained.

Water evaporates, hits the glass, turns into droplets, and then falls back into the soil. It keeps going like that. This loop keeps humidity steady and the plants happily watered—making it considerably low maintenance.

The plants that work here are the ones that don’t mind humidity. Moss, fern, and fittonia are some common examples. These enjoy being in a slightly damp, enclosed space.

The upside? You’re not watering it every few days. Sometimes you forget about it for weeks, and it’s still fine.

The downside, though, is that if something’s off, it can stay off. Too much water, and you’ll notice the glass staying foggy all day. It might even grow a bit of mould. 

And sunlight matters more than you’d expect. Too much direct sun and it heats up fast, like leaving a water bottle in the car. Even a few minutes of strong sunlight can stress or scorch the plants inside, so keep them in bright, indirect light whenever possible.

Open Terrariums 

Open terrariums are exactly what they sound like. There is no lid, air comes in freely, and moisture goes out each second.

So instead of recycling water like the closed ones, these dry out over time. Which means you do have to water them, but not as often as a typical potted plant, and it’s easier to adjust if they start to look dry.

This setup works better for plants that don’t want to sit in moisture all day. Succulents, cacti, those compact little plants that look nice even if you forget about them for a bit—they like light and airflow, and dislike being damp.

Visually, open terrariums feel a bit more minimalist. You’ll see more space between plants, maybe some sand or stones, and cleaner layouts overall.

They’re easier to fix, too. If something looks off, you can adjust it right away. No trapped humidity to complicate matters.

Regular monitoring is necessary, however, as neglect can cause plants to dry out or deteriorate.

So Which One Is Better?

The choice depends on your preferences and routine.

If you tend to forget to water plants, closed terrariums are a reliable option. Once established, they largely maintain themselves.

If you don’t mind occasional maintenance and have a well-lit location, open terrariums offer more control and fewer risks of hidden issues.

Some individuals choose to have both types: one for a lush, dense appearance and another for a cleaner, more structured look.

A Straightforward Comparison

Closed	Open
Holds moisture	Dries out over time
Needs very little watering	Needs occasional watering
Good for moss, ferns	Good for succulents, cacti
Feels more “alive” and dense	Feels cleaner and more styled
Can get too humid if overwatered	Can dry out if ignored

A Note on Making One

Building a terrarium involves more than simply arranging plants—it’s about layering, positioning, and adjusting elements until the arrangement feels balanced. The process is straightforward, yet highly satisfying.

It’s an activity suited for a leisurely afternoon, offering a mindful break from screens.

J2 Terrarium emphasises this hands-on experience in our workshops. The approach is approachable and non-technical: participants create their own terrariums and leave with a finished, personalised arrangement.

The workshops are suitable for individuals, small groups, or corporate events, providing a low-effort and memorable experience. If you would like to experience this as soon as possible, click here to reserve your spot in our terrarium-making workshop!

Quick FAQs

Can I switch a closed terrarium to open later on?

You can do so, but the plants may not respond well to the change. The outcome depends on the species used.

Do terrariums attract bugs?

Terrariums generally do not attract insects, unless there is excessive moisture or decaying plant material.

Are terrariums good for small spaces?

Terrariums are particularly well-suited for small spaces, such as desks, shelves, or corners that could use a touch of greenery.

Have more questions? Contact us to get expert guidance or to arrange a workshop tailored for you.