A closed terrarium is a tiny, self-sustaining world. Here's how to keep it thriving — mostly by staying out of its way.
A terrarium isn't really a plant in a jar. It's a small, closed world with its own weather. Water rises off the soil and leaves, gathers on the glass, and trickles back down like rain. The plants breathe, the moss drinks, and the whole cycle repeats — quietly, on its own, without you.
People often treat a terrarium like a houseplant that needs constant attention, when really it needs the opposite. Most terrariums don't die of neglect. They die of too much water, too much fussing, too much "just checking on it." The real skill of terrarium care is knowing when to leave it alone.
Here's everything you actually need to do, and not much more.
Mist it, don't water it
A terrarium doesn't get watered like a potted plant. It gets a light misting using a spray bottle, and only when it truly needs one. Usually 2-3 times a month is enough.
If you pay close attention, it will tell you when it needs water - the plants, especially Fittonia would start drooping. When that happens, give it a few sprays, then walk away. Inside a closed terrarium, the same water is recycled over and over, so it needs far less than you'd think.
When in doubt, do nothing — a slightly dry terrarium recovers easily, a waterlogged one does not.
Give it bright, indirect light
Terrariums love light, but not direct sun. A bright spot away from the window is perfect. Direct sunlight turns the glass into a little greenhouse-oven and will cook the plants inside. It shortens your terrarium's life rather than helping it grow.
If your space doesn't get much natural light, a simple grow light does the job well. A few hours a day is plenty.
Keep the glass clean
This one's easy to forget. Dust settles on the glass slowly, and because it happens so gradually, you don't notice the light dimming inside. But your plants do. Whenever the jar looks less than crystal clear, give it a quick wipe.
Clean glass means more light reaches the plants and it looks better!
Let it breathe once a week
Here's the one small ritual worth keeping: once a week, take the lid off for about five minutes. That's it. It lets a little fresh air in, keeps things from getting stale, and helps your terrarium stay healthy for the long run. Then pop the lid back on and let it get on with its life.
A terrarium rewards patience more than effort. The best thing you can do is enjoy watching it - a whole living world, quietly taking care of itself on your shelf
Common questions
We've compiled a list of questions that customers have asked us after making or buying a terrarium from Planterie
Is the fog on the glass normal?
Completely. That misty condensation is your terrarium's water cycle doing exactly what it's supposed to — proof the little ecosystem is working, not a warning sign. The only time to pay attention is when the fog is constantly heavy and the soil underneath looks soggy. That means there's a bit too much water in there. Just leave the lid off for a few hours to let the extra moisture escape, then close it back up.
Why does my terrarium keep drying out?
If it's dry no matter how often you mist, the problem is usually where it's sitting. A spot that heats up past 40°C — say, right beside a sunny window — will dry it out faster than you can keep up with. Move it somewhere cooler with bright, indirect light (or under a grow light), and it should start holding moisture the way it's meant to.
There's mold or fungus inside — what do I do?
Don't panic. This almost always means something from outside the terrarium's own little world snuck in — a stray leaf, or an element that wasn't fully clean. Take the lid off to air the container out, then gently wipe away any visible mold with a cotton swab or a piece of paper towel. Once the intruder's gone, the ecosystem usually rights itself.
