What a terrarium is

A build is one short sitting: you layer the jar, plant it with tweezers, wipe the glass and close the lid. Everything after that is observation and small corrections. For the first two weeks you adjust the lid until the moisture settles. Then the job shrinks to a glance each day and a trim every month or two. Most people do not stop at one. The second jar is where you start composing: a slope, a stone, a taller plant at the back.

A person in a green beanie lowering a long tool into a narrow glass bottle on a wooden workbench — Planting a bottle with a long tool

The layers, from the bottom up

Read it like the jar: 1 goes in first

Drainage layerAbout an inch of clay pebbles or small stones. A jar has no drain hole, so extra water needs somewhere to sit below the roots.
BarrierA thin sprinkle of charcoal keeps soil from washing down into the pebbles. Whether charcoal also keeps a jar fresh is argued about, but it is cheap and does no harm.
SubstrateTwo to three inches of a loose, chunky mix that holds moisture without packing down. Dense garden soil stays soggy and rots roots.
Plants and mossSmall plants that like constant humidity. Moss fills the gaps and covers bare soil.
Air spaceLeave the top third of the jar empty. Plants need room to grow into, and a jar packed to the lid cannot be trimmed.

Choosing a jar and plants

Clear glass only

Tinted or frosted glass cuts the light plants get. Plastic scratches and clouds.

A mouth your hand fits through

A wide opening makes the first build easy. Narrow-necked bottles look good but turn planting into keyhole surgery.

A lid that closes

Cork, glass or a clamp top all work. A loose glass lid that lets a little air through is easier to balance than an airtight seal.

Half a gallon to a gallon

Smaller jars swing from wet to dry fast and leave no room for roots.

Plants that stay small and love humidity

Nerve plant, baby tears, creeping fig, small ferns and miniature peperomia are the reliable choices. Buy them in 2-inch pots.

No succulents or cacti in a closed jar

They need dry air and rot within weeks behind glass.

A cone-shaped glass jar with a knobbed glass lid, planted with moss and pink-veined nerve plants over sand and soil — A lidded jar planted with moss and nerve plants

Build your first jar

A second walkthrough to build beside

University of Missouri Extension: Terrariums A free, plainly written guide to containers, layers, plant choice and care from a horticulture program

What you can build in your first month

A closed tropical jar

Two or three small foliage plants over pebbles and soil, lidded. The standard first build, and the one that teaches you to read condensation.

A moss jar

Nothing but live moss and a stone or two in a small lidded jar. Moss forgives clumsy planting because it has no roots to damage.

A marimo jar

Two or three green algae balls in a jar of cool water. There is nothing to plant, so it is done in five minutes.

A sealed pond jar

Gravel, a few water plants and pond water, sealed for good. It clouds, clears and settles over the first weeks, and that is the show.

A snail on moss behind fogged glass beaded with water droplets

Keeping it balanced

The glass tells you what the jar needs

Read the glass

Light fog in the morning that clears by afternoon means the moisture is right. Heavy droplets running all day mean too wet. Dry glass for days means too dry.

Light

Bright and indirect. Direct sun through glass can cook a closed jar in an afternoon.

Water

A balanced closed jar may need a few sprays every month or two, sometimes less. Use distilled water or rainwater so the glass does not collect white mineral spots.

Trim

Pinch off any leaf that touches the glass, and remove yellow or dead leaves the day you see them so they do not feed mold.

Turn it

A quarter turn each week stops everything leaning toward the window.

Three directions after your first jar

Moss gardeningA mossarium is a jar planted with nothing but moss and stone. It stays low, grows slowly and looks like a hillside seen from the air.

Start here

Fill a shallow layer of pebbles and soil in your jar, press live cushion moss onto it so every piece touches the soil, mist it and close the lid. Keep it out of direct sun.

Terrarium Tribe: moss terrarium guide

Sealed jar ecosystemsA jar that is set up once and sealed for good. The classic version is a pond jar, where water plants, snails and microscopic life keep each other going.

Start here

Rinse a handful of gravel, add a few low-light water plants, fill the jar three quarters full with pond water or dechlorinated tap water and seal it. Leave it in bright shade and resist opening it.

r/Jarrariums

Marimo moss ballsVelvety green spheres of algae that live in a jar of plain water. They grow about a fifth of an inch a year and can outlive their owner.

Start here

Inspect each ball for tiny striped shells, then drop them into a jar of cool tap water somewhere out of direct sun. Change the water every two weeks and roll each ball in your palms so it stays round.

U.S. Fish & Wildlife Service: zebra mussels in moss balls

Open a card for a first step. Its button adds that direction's lines to the kit.

Read before you seal or buy

What trips beginners up

White fuzz in week two

Almost every new jar grows a little mold while it settles. Pick out the affected bit, air the jar for a day and it usually does not come back.

It will not be maintenance free on day one

The stories about jars sealed for decades are real, but those jars took months of small adjustments first.

Some plants will not make it

Losing one plant in a first build is normal. Pull it and replant the gap.

Overwatering

The most common way to kill a jar. Water you add never leaves, so add it by the spray, not by the cup.

Cramming it full

Plants double in size within months. Three small plants are enough for a one-gallon jar.

Collecting from the wild

Taking moss from parks and public land is often against the rules and brings in pests. Buy it, or take a little from your own yard.

An open glass vase holding a slope of bright moss and a few small ferns, lit against a dark room — Moss and a few small ferns, with room left to grow

Where to learn more

Terrarium building is taught mostly through photos and video, and the good material is free. Start with one written guide so the layer order sticks, then watch a few full builds to see how plants are handled with tweezers. Videos that revisit a jar months later teach more than the build itself. When something looks wrong, post a clear photo to a terrarium community: mold, gnats and yellow leaves are asked about daily and the answers come fast.

Free guides, builds and a place to ask

How the kit is put together

The jar and the plants are where the money goes, and the jar is the part you can skip if a large pickle or storage jar is already in your cupboard. The layers are sold in bags far bigger than one jar needs, so the second and third builds cost only plants. The tools matter more than they look: fingers do not fit, and kitchen tongs crush stems. Each of the three directions adds one or two lines of its own and reuses the same jar and tools. The two optional lines solve specific problems: a cleanup crew for jars that keep molding, and a small light for rooms without a bright window.

White trays holding moss, black charcoal pellets, white pebbles and tan granules beside an empty glass jar — Moss, charcoal, pebbles and substrate laid out in trays

Fill the jar

Compare the options on each line, then set your tiers and check out from the cart. Clicking a card selects it there. The jar, the layers, the plants, the tools and the mister start in the kit. The moss, pond jar and marimo lines join when you switch on their direction. The cleanup crew and the grow light start out of it.

Glass terrarium jar with lid

Essential · Container

The jar is the whole habitat. A lid is what turns a pot of plants into a terrarium that waters itself.

budget

North Mountain Supply 1 Gallon Wide-Mouth Glass Jar with Lid

4.7(1,681)

$13.50

Terrariums

What a terrarium is

The layers, from the bottom up

Choosing a jar and plants

Build your first jar

Keeping it balanced

Three directions after your first jar

What trips beginners up

Where to learn more

How the kit is put together

Fill the jar

Glass terrarium jar with lid

Clay pebbles for the drainage layer

Terrarium substrate mix

Small live terrarium plants

Horticultural charcoal

Long terrarium tool set

Fine-mist spray bottle

Live cushion moss

Small landscape stones

Aquarium gravel

Live low-light aquarium plants

Live marimo moss balls

Live springtail culture

Small LED grow light