You found the perfect jar at a thrift store. You imagined moss, tiny ferns, maybe a miniature world that would basically take care of itself. You followed a tutorial, planted carefully, sealed it up. Three weeks later, you’re staring at brown mush and wondering what you did wrong.
Here’s what nobody told you upfront: your beautiful plants didn’t die because you lack a green thumb. They died because you built the wrong type of terrarium for those specific plants.
Most guides throw plant lists at you without explaining the fundamental choice that determines everything. The lid or no lid decision creates entirely different climates inside your glass. One traps humidity like a rainforest. The other breathes like a desert plateau. Your fittonia needed constant moisture. Your succulent needed dry air. And nobody explained that before you started.
But we’re going to fix that right now. We’ll walk through seven distinct terrarium types together, matching them to real plants, real spaces, and your actual daily life. By the end, you’ll know exactly which type fits you, and you’ll build it with confidence instead of crossed fingers.
Keynote: Terrarium Types
Terrarium types fall into two primary categories based on air exchange: closed terrariums that seal moisture inside, creating self-sustaining humid ecosystems, and open terrariums that allow airflow for plants requiring drier conditions. Beyond this fundamental split, specialized types like bioactive systems, paludariums, bottle gardens, hanging terrariums, and Wardian cases serve specific aesthetic, spatial, or ecological purposes.
The Fork in the Road: Open or Closed (And Why This Single Choice Changes Everything)
The question that decides your plant’s fate
Do you seal the top or leave it open? This isn’t decoration. It’s climate control.
A lid traps humidity and creates a mini rainforest cycle inside glass. No lid means air flows freely, mimicking dry desert or savanna conditions. Your answer determines which plants live and which ones slowly rot away.
I learned this the hard way when my first “just follow the pretty Pinterest photo” terrarium turned into a graveyard. I’d sealed succulents in a corked jar because it looked stunning. Two weeks later, the echeveria leaves were translucent mush and the whole thing smelled like decay.
The closed world: a self-watering rainforest in a jar
Sealed terrariums recycle their own water through evaporation and condensation. Moisture rises from soil, condenses on glass, drips back down like tiny weather happening inside your container.
You might water once a month, or even less frequently after the system balances. My friend Emma has a closed fern terrarium on her Seattle bookshelf that she’s watered exactly three times in seven months. Every time I visit, it’s greener and fuller than before.
This is your home for ferns, moss, and any plant that loves humidity. The condensation cycle you’ll see on the glass? That’s not a problem. That’s proof the ecosystem is working.
The open garden: breathing room for plants that hate wet feet
Open terrariums let moisture escape, keeping the environment drier and airier. These need regular watering, maybe weekly or biweekly, unlike their sealed cousins.
Succulents and cacti belong here, never in a sealed humid trap. Think of it this way: if the plant grows in a desert, it needs to breathe. If it grows under a rainforest canopy, it wants that greenhouse effect.
I keep an open dish garden on my kitchen windowsill with haworthia and a small jade plant. Every Sunday morning while coffee brews, I check the soil and water if it’s bone dry. That’s it. The routine takes 90 seconds.
At a glance: which type matches your plants?
| Feature | Closed Terrarium | Open Terrarium |
|---|---|---|
| Humidity Level | High (70-100%) | Room level (40-60%) |
| Watering | Rare (monthly or less) | Regular (weekly to biweekly) |
| Best Plants | Ferns, moss, tropical plants | Succulents, cacti, air plants |
| Light Needs | Bright indirect only | Can handle more direct sun |
| Beginner Risk | Mold if overwatered | Root rot if drainage fails |
| Maintenance Feel | Set it and mostly forget it | Weekly check-ins and adjustments |
The table makes it look clean and simple, but here’s the real lesson: match the plant’s natural home to your terrarium’s climate. Desert plants get open air. Jungle plants get sealed humidity. Everything else is just details.
The Closed Terrarium: Your Tiny Rainforest That Waters Itself
The magic of the water cycle you can watch
Inside sealed glass, water evaporates from soil, rises, condenses on cool glass surfaces. That misty fog you see in the morning? That’s transpiration happening, plants releasing water through their leaves as they photosynthesize.
The moisture drips back down, completing a miniature version of Earth’s hydrologic cycle. When this loop balances perfectly, you barely touch it for months. I’ve watched this process in the closed jar on my desk, the one that survived a three-week vacation without anyone opening it once.
According to the University of Missouri Extension, properly balanced closed terrariums can maintain themselves for extended periods because they create self-sustaining ecosystems through this natural water cycling process.
Plants that actually thrive in humid captivity
Small ferns bring that delicate, lacy look everyone craves without demanding floor space. Button ferns and maidenhair varieties stay compact and forgive the occasional closed-lid mistake.
Moss creates a living carpet that holds moisture and completes the forest floor vibe. I use sheet moss as a base layer in most of my closed builds because it stabilizes everything underneath.
Fittonia, the nerve plant with those dramatic white or pink veined leaves, absolutely loves constant humidity. It’ll throw a fit and droop in dry air, but seal it in glass and suddenly it’s the happiest plant you own.
Peperomia varieties stay compact, tolerate lower light than you’d expect, and forgive small watering mistakes. The prostrata variety trails beautifully without taking over the entire container.
One warning: avoid fast-growing vines like pothos in small closed terrariums. They’ll smother everything else within three months and you’ll be constantly pruning through that narrow opening.
The mistake that kills closed terrariums every single time
Direct sunlight on sealed glass turns your terrarium into a plant oven. Heat magnifies inside, condensation covers every surface, leaves cook and collapse within hours on a truly hot day.
I placed a sealed jar terrarium on a sunny table once, thinking more light meant happier plants. By afternoon the glass was too hot to touch comfortably. The fittonia inside looked like wilted lettuce. I moved it immediately to a shaded shelf and it recovered, but barely.
Place near bright windows but never where sun beams hit the glass directly. Your closed terrarium needs the light for photosynthesis but not the magnified heat that comes with it.
Too much fog covering the glass all day long? You started with too much water. Crack the lid for a few hours, let excess moisture escape, then reseal. The condensation should clear mostly during the day and return lightly at night.
The truth about drainage layers and activated charcoal
A gravel or pebble drainage layer at the bottom can help prevent root rot in closed systems by creating space where excess water can collect away from roots.
But here’s the honest take: it isn’t always required if you water carefully and use well-draining substrate. I’ve built successful closed terrariums both ways. The drainage layer gives you a buffer for mistakes, but good technique matters more.
Some experts swear by activated charcoal mixed into the substrate or layered separately, claiming it filters water and prevents odors. Others say it’s completely optional and does nothing measurable in a healthy terrarium.
My take after building dozens of these? Charcoal doesn’t hurt, might help slightly, but your watering discipline and plant choices determine success far more than any magic ingredient at the bottom.
The Open Terrarium: Dry Air and Sculptural Beauty
Who loves the breathing room of an open top
Succulents store water in thick leaves and hate constant humidity. The crassula family, echeveria rosettes, and compact aloe varieties all need air circulation to prevent the rot that kills them in sealed jars.
Cacti need dry air to thrive, making open dishes their only viable home. I keep a small golden barrel cactus in a shallow ceramic bowl with two mammillaria companions. They’ve lived there for two years with minimal fuss.
Air plants, those wild tillandsia species that seem to defy basic plant logic, absorb moisture from air and occasional misting. No soil needed. They perch on driftwood or nestle in gravel, pulling what they need from humidity and weekly soaks.
Mediterranean herbs can work in open terrariums if you provide strong light and excellent drainage. I’ve seen rosemary and thyme survive in shallow glass dishes on south-facing windowsills, though they’re finicky about it.
Airflow is the silent ingredient that prevents disaster
Moving air lets leaves dry between waterings, stopping mold before it starts. Stagnant air plus moisture equals fungal problems within days.
Place your open terrarium where gentle air circulates naturally. Not beside heating vents that blast dry wind, but also not in a dead-air corner where nothing moves.
Watch for fuzzy white growth appearing on soil surface. That’s your airflow alarm screaming that moisture is sitting too long without evaporating. When I see that, I immediately move the container to a spot with better circulation and cut back watering by half.
The gravel in a healthy open terrarium should feel crunchy and dry to touch on top. If it feels damp and cold hours after watering, you’ve got a moisture retention problem that needs fixing.
The watering rhythm that feels counterintuitive but works
Water less than your gut tells you, then wait and observe how the plants respond over several days.
Teach yourself the finger test: poke the soil an inch deep. It should feel barely damp, never wet enough to leave moisture on your skin. For succulents especially, underwater first, then adjust up only if plants look shriveled or wrinkled.
Let the top inch of soil dry completely between waterings. This goes against every instinct if you’re used to houseplants that want consistent moisture, but desert plants evolved for feast or famine cycles.
I water my open succulent dish every 12 to 14 days in winter, maybe every 9 days in summer when evaporation runs faster. That’s it. Less really is more here.
Building layers that won’t betray your dry-loving friends
Start with a deep drainage layer, at least one inch of pebbles or LECA clay balls, to catch any excess water and prevent soggy roots.
Use sandy, gritty soil that dries quickly. Never use moisture-retaining tropical mixes designed for ferns and philodendrons. I mix regular potting soil with coarse sand and perlite at a 1:1:1 ratio for most open terrariums.
Avoid the temptation to pack soil down tight when planting. Loose, airy texture lets roots breathe and water drain. Compressed soil holds water like a sponge and kills succulents fast.
Research suggests roughly 75% of succulent deaths in terrariums trace back to poor drainage and water retention issues, not the plants themselves being difficult.
Bottle Gardens and Narrow-Neck Challenges: Beautiful but Demanding
What changes when the opening shrinks
Planting through a narrow bottle neck feels like delicate surgery. Your hands don’t fit. Regular tools are too wide. Every movement needs precision because corrections happen in slow motion.
I spent an hour placing three small plants into a wine carafe for my first bottle garden attempt. My hands cramped. I knocked over the same fern cutting twice. But when I finally sealed that cork and stepped back, the accomplishment felt bigger than the frustration.
Every placement decision matters more when you can’t easily rearrange later. Plan your layout on paper first. Visualize where each plant goes before you commit to the tight-space dance.
The bottle garden as its own closed ecosystem
Bottle gardens are essentially closed terrariums housed in glass bottles with narrow openings. They follow all the same principles: trapped humidity, condensation cycling, self-sustaining moisture if balanced correctly.
They can remain stable for incredibly long periods if light stays gentle and indirect. There are documented examples of bottle gardens thriving for decades with minimal intervention, living proof that Dr. Nathaniel Bagshaw Ward’s Victorian-era discovery about sealed plant environments was absolutely legitimate.
Note the heat risk: bottles in direct sun build internal temperatures faster than wide-mouth jars because the glass curvature focuses light. Heat kills sealed plants within hours on a hot summer day.
The narrow opening actually helps maintain consistent humidity once you seal it properly. Less air exchange means more stable conditions, which plants appreciate once the initial balance establishes.
Tools and tricks that save your patience
Long tweezers or chopsticks become your planting hands inside tight spaces. I keep 12-inch bamboo chopsticks and needle-nose tweezers specifically for bottle work.
Tape a small spoon to a wooden dowel for moving soil without smearing the interior glass walls. You can build this tool in 30 seconds with masking tape and it saves endless frustration.
Create a paper funnel for pouring substrate layers cleanly. Roll parchment paper into a cone, insert the narrow end into your bottle, and pour gravel or soil without coating the glass in grit.
Clean the glass last with a cloth wrapped around a chopstick, secured with a rubber band. Work in circular motions, removing all the soil smudges and fingerprints for that satisfying final reveal.
Beyond Basic Builds: Bioactive Systems and Specialty Worlds
The self-cleaning upgrade: what “bioactive” actually means
Bioactive terrariums include tiny cleanup crews, living organisms like springtails and isopods that eat mold, decompose dead leaves, and process waste naturally.
These microfauna create a genuine decomposition cycle inside your terrarium, turning plant debris into nutrients that feed everything else. It’s a closed-loop ecosystem that handles its own maintenance.
It sounds complex, but adding a springtail culture to any closed terrarium is surprisingly simple. You order them online, sprinkle them into your substrate, and they multiply on their own schedule without your involvement.
Think of it as hiring a microscopic janitorial staff for your mini world. They work 24 hours a day, you never see them doing it, and your terrarium stays cleaner than it would otherwise.
The cleanup crew you’ll genuinely want in your jar
Springtails are tiny white jumping insects, barely visible to the eye, that devour mold before it spreads across soil and glass. They’re the first line of defense against the fuzzy white growth that kills aesthetic appeal.
Isopods, those little pill bugs you find under rotting logs, break down dead plant matter into rich, usable compost. They need moisture to survive, making them perfect companions for humid closed setups.
Both species coexist peacefully with plants and each other. I added them to my largest closed terrarium eight months ago and the soil looks healthier now than when I first built it.
Order starter colonies from specialty suppliers and they’ll reproduce naturally without overcrowding. The population self-regulates based on available food, so you never end up with an infestation.
When your terrarium includes animals: vivariums and paludariums
Terrariums prioritize plants. Vivariums prioritize housing animals, with plants serving as habitat elements rather than the main feature.
Paludariums blend land and water sections in one container, creating shoreline ecosystems with both terrestrial and aquatic zones. Half the container might hold water with aquatic plants while the other half stays dry for ferns and moss.
These require serious planning beyond basic terrarium knowledge. Ventilation becomes critical for animal health. Heating, lighting, water filtration, and species-specific welfare research all enter the equation.
Attempt these only after successfully maintaining basic closed and open terrariums for at least six months. Animal welfare always comes before aesthetic dreams, and rushing into vivarium builds without experience causes suffering.
If you’re genuinely interested in bioactive vivariums and paludariums, The Bio Dude’s detailed setup guides provide comprehensive information on substrate cycling, cleanup crew ratios, and proper environmental parameters.
The Wardian Case: History’s Accidental Gift to Plant Lovers
The 1829 discovery that changed everything
Nathaniel Ward wasn’t trying to invent terrariums. He was a London physician studying moths, keeping them in sealed glass jars to observe their life cycles.
A fern spore accidentally germinated in the soil at the bottom of one jar. Ward noticed it thriving despite receiving no water, no fresh air, just indirect light through the glass. This quiet curiosity became an obsession that revolutionized global plant transport.
He experimented systematically for years, documenting how plants survived sealed in glass for extended periods, recycling their own moisture through condensation and transpiration. His findings seemed almost magical to Victorian botanists.
The Wardian case was born from that accidental fern. Decorative sealed glass containers became fashionable in parlors across England, but more importantly, they enabled botanical exploration on a scale previously impossible.
Why this matters beyond your coffee table decoration
Wardian cases enabled live plants to survive brutal months-long sea journeys from tropical colonies back to European botanical gardens. Before Ward’s invention, maybe one in a hundred plants survived ocean transport. After, the success rate jumped dramatically.
Exotic species traveled between continents for the first time in viable condition. Tea plants went from China to India. Rubber trees from Brazil reached Southeast Asia. This wasn’t just hobbyist gardening; it reshaped agriculture and colonial economics.
The principle remains identical to what we do today: create stable, protected microclimates that resist outside chaos. Your sealed jar on the bookshelf operates on the same science that transported plants across oceans in the 1800s.
Royal Botanic Gardens Kew calls Wardian cases a complete game changer for botanical science, and they’re not exaggerating. Modern terrariums are direct descendants of that accidental moth jar fern.
The lesson that matters for your build today
Stability beats constant fussing every single time in closed systems. Make tiny adjustments, then step back and observe for days before changing anything again.
Your jar can genuinely self-sustain when you resist the urge to meddle daily. Ward’s original experimental ferns thrived because he left them alone, trusting the natural cycling process.
I remind myself of this whenever I’m tempted to open my closed terrarium just to check on things. History proves this works when we trust the process and give the ecosystem time to stabilize.
Hanging Terrariums and Mossariums: Specialized Aesthetic Choices
When vertical space becomes your gardening frontier
Hanging terrariums utilize wall and ceiling space that otherwise sits empty, turning dead air into living decoration. Glass orbs suspended by twine or mounted tear-drop containers create floating gardens that draw the eye upward.
These work best as open containers because accessing them for maintenance gets complicated when they’re hung high. You don’t want to be reaching overhead with a watering can weekly, sloshing water everywhere while standing on a chair.
I hung three small glass orbs near my kitchen window, each with a different air plant variety. They catch morning light beautifully and need nothing but a weekly misting with a spray bottle on a long handle.
The trick is keeping them light enough that your hanging hardware holds safely. Heavy soil and water add up fast. If you want a closed hanging terrarium, keep it small and hang it from something structural.
Mossariums: when one plant type does all the work
A mossarium is exactly what it sounds like: a terrarium dedicated entirely to moss species. No companion plants, just different moss varieties creating a miniature forest floor landscape.
Moss loves humidity and low to moderate light, making closed containers perfect. You can create incredible depth and texture using just sheet moss, cushion moss, and fern moss together in layers.
I built one in a shallow glass bowl with a fitted lid, using three moss types collected from a local forest on a rainy November walk. Eight months later it’s still lush green, watered maybe five times total.
The maintenance is almost nonexistent. Moss doesn’t grow fast enough to need pruning. It doesn’t require fertilizer. It just sits there being green and ancient-looking while you ignore it completely.
Common Type Mistakes That Quietly Destroy Terrariums
The classic overwatering death spiral
You see a drooping leaf, panic sets in, and you add water to fix it. But the drooping wasn’t from thirst; it was from roots already suffocating in saturated soil.
One simple rule saves you here: if condensation covers the glass all day long, stop watering immediately. The system has too much moisture already. More water just accelerates root rot.
Crack the lid open briefly, maybe an hour or two, to increase airflow and let excess moisture escape. Then reseal and observe for several days before doing anything else.
Remember, you watered because you cared about your plants, not because you failed at terrarium keeping. Overwatering happens to everyone. The trick is catching it early and correcting course.
Plant mismatch: the silent relationship killer
Sealing succulents in humid jars rots them from the roots up within two to three weeks. The thick leaves turn translucent, then mushy, then collapse entirely.
Placing moisture-loving moss in open, dry air crisps and browns it fast. It loses that vibrant green and turns into something that looks like dried herbs.
Ask yourself one question before placing any plant: where does this naturally grow? Humid tropics or dry desert? Match that climate to your terrarium type and you’ve solved 90% of potential problems.
If you’re not sure, search the plant name plus “natural habitat” and you’ll know within 30 seconds whether it needs open or closed conditions.
The sunlight trap nobody warns you about clearly enough
Glass plus direct sun equals a greenhouse effect that literally cooks sealed terrariums. The temperature inside can spike 20 to 30 degrees above room temperature within an hour.
Use this sensory warning: if the glass feels hot when you touch it, your plants are suffering inside. Wilting leaves, sudden collapse overnight, and condensation that looks more like steam are all heat damage signals.
Offer bright but indirect light, especially critical for closed humid builds. Place near windows but offset to the side where direct beams never hit. For open terrariums, some gentle direct morning sun can work without overheating since air escapes.
I moved every terrarium in my apartment at least once before finding their permanent homes. Trial and error taught me where each spot’s light patterns actually land throughout the day.
The “I must tinker constantly” mindset
Stability is your actual goal, not daily adjustments and constant interventions. Every time you open a closed terrarium, you’re disrupting the established humidity and temperature balance.
Try weekly check-ins instead of daily panic sessions over every tiny change. Look for genuine problems like mold spreading, plants clearly dying, or condensation patterns that seem wrong.
Celebrate the small wins: new growth, fresh fern fronds unfurling, moss spreading slightly. These are your terrarium saying you’re doing great, so step back and let it continue.
I used to check my first closed terrarium twice a day, opening it to touch the soil, adjust a leaf, investigate every water droplet. The plants looked stressed and stalled. When I forced myself to weekly checks only, everything improved within a month.
Matching Terrarium Type to Your Actual Life (Not Your Pinterest Dreams)
The honest assessment of your space and schedule
Does your room get bright indirect light for most of the day, or only dim ambient glow from north-facing windows? That decides which plants will actually photosynthesize successfully.
Can you commit to weekly watering routines, or do you need total set-and-forget reliability because your schedule is chaotic? There’s no wrong answer, but be honest about it.
Are you drawn to lush tropical greens that feel like miniature jungles, or clean minimalist desert sculptures with architectural forms? Your aesthetic preference matters because you’ll look at this daily.
Beginners should start with either open succulent terrariums or simple closed tropical setups. Both forgive mistakes better than specialized builds and teach you the fundamental principles.
The lighting reality nobody wants to talk about
Closed tropical terrariums need bright indirect light for 8 to 12 hours daily to maintain healthy photosynthesis. Low light means slow, leggy growth and eventual plant decline.
Open desert setups can handle some direct sun but still need careful placement monitoring. Too much and you’ll bake the roots. Too little and succulents stretch and lose their compact form.
North-facing windows rarely provide enough natural light without supplemental grow lights. I learned this when my north-window terrarium slowly faded over three months despite perfect watering.
Insufficient light kills more terrariums than overwatering does, but it kills slowly and subtly, so people don’t connect cause and effect until it’s too late.
Time commitment: the truth about each type
Closed terrariums demand about 10 minutes monthly once balanced. You’ll crack the lid if condensation runs heavy, add a few drops of water if the soil looks bone dry, maybe trim one overgrown plant.
Open succulent terrariums need 15 to 20 minutes weekly. You’ll water when soil is dry, check for rot on lower leaves, clean the glass if it’s dusty, remove any dead material.
Bioactive setups require roughly 30 minutes monthly for feeding the cleanup crew if needed, pruning any overgrowth, and monitoring the microfauna population balance.
Paludariums demand 1 to 2 hours weekly for water changes, filter cleaning and maintenance, aquatic plant trimming, and checking parameters if you’re housing animals.
Cost breakdown: what you’ll actually spend
Basic open succulent terrarium: $15 to $30 total for a small glass dish, drainage pebbles, succulent soil mix, and three small plants from a garden center.
Standard closed tropical terrarium: $40 to $80 for a quality glass jar with lid, substrate layers, small tropical plants, and possibly a springtail culture if you want bioactive benefits.
Bioactive terrarium with cleanup crew: $100 to $150 when you add isopod and springtail cultures, specialized ABG substrate mix, and slightly larger container to support the ecosystem.
Advanced paludarium build: $200 and up depending on size, filtration system, heating elements, quality of glass container, and the specific animals you plan to house.
You can cut costs by using recycled glass jars, collecting local moss legally, and propagating plants yourself instead of buying full-sized specimens. My cheapest successful terrarium cost me exactly $8 using a thrift store jar and garden soil.
Conclusion: The Terrarium Type That’s Been Waiting for You
You started this journey overwhelmed, staring at conflicting advice and fearing another brown, mushy failure in your future. But now you understand the core truth that changes everything: the container is your climate machine, not just a pretty jar. Open creates dry breathing room for desert lovers. Closed traps humid stability for tropical plants. Match that climate to your plants’ natural homes, and suddenly everything clicks into place.
Maybe you’re ready for a low-maintenance closed tropical world that cycles its own water while you work long hours and travel frequently. Maybe you’re drawn to sculptural succulents in an open dish that forgives your weekend watering routine. Maybe you’re even ready to add springtails and build a true bioactive ecosystem that maintains itself. Whatever calls to you, it’s the right choice if it matches your real life, not the fantasy version.
Your single actionable step for today: Look at the exact spot where you want your terrarium to live. Is the light bright or dim? Does direct sun hit that surface? That one observation just told you if you need open or closed. Write it down. Then choose three plants that thrive in that specific climate condition and make your shopping list. That’s it. You’re not researching for another week. You’re choosing and starting.
You’re not just building a terrarium. You’re building confidence, one tiny self-sustaining world at a time. The jar that failed before? That taught you what doesn’t work. This one will teach you what does.
Types of Terrarium (FAQs)
What is the difference between open and closed terrariums?
Yes, there’s a major difference. Closed terrariums seal moisture inside and create humid, self-watering ecosystems perfect for ferns and tropical plants. Open terrariums allow air circulation and stay drier, which suits succulents and cacti that hate constant humidity. The lid decision determines which plants survive.
Which terrarium type is easiest for beginners?
Yes, closed tropical terrariums are often easiest for true beginners. They require minimal watering once balanced, maybe monthly or less, and forgive irregular attention better than open types. Choose slow-growing moss and small ferns rather than aggressive vines. Alternatively, open succulent dishes work great if you can commit to weekly watering checks.
Can you put succulents in a closed terrarium?
No, absolutely not. Succulents evolved for dry desert conditions and storing water in their thick leaves. Sealed humid environments cause root rot and leaf collapse within weeks. Succulents need open terrariums with excellent airflow and drainage. This mismatch kills more beginner terrariums than any other single mistake.
What type of terrarium needs less water?
Closed terrariums need less water because they recycle moisture through condensation cycling. Once balanced, you might water monthly or even less frequently as the water evaporates and condenses in a continuous loop. Open terrariums need regular watering, typically weekly to biweekly, because moisture escapes into the room air.
Do closed terrariums need to be opened?
Yes, but only occasionally for maintenance and balance adjustments. Crack the lid briefly if condensation covers the glass all day, indicating too much moisture. Open it to trim overgrown plants or add water if the soil looks bone dry. Most of the time, keep it sealed to maintain the humid microclimate your tropical plants need.