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How to make a terrarium: a step-by-step guide

A terrarium is a small garden grown inside a glass container. Set up well, it needs very little care; a closed terrarium can go for months without watering. This guide walks through every step, from choosing the container to looking after it in the first months.

How to make a terrarium: a step-by-step guide
Photo: christopher*, CC BY 2.0 · Wikimedia Commons
Difficulty
Easy–moderate
Time
1–2 hours
Cost
Low; most materials are around the house
Care
Closed: check monthly. Open: water every 1–3 weeks (estimated)

Open or closed?

The first decision is whether the terrarium will have a lid, because that decides which plants you can use.

Closed terrarium

  • Sealed with a lid or stopper.
  • Water evaporates, condenses on the glass and drips back down — a tiny water cycle of its own.
  • High humidity: for moisture lovers like ferns, moss and fittonia.
  • Watered very rarely.

Open terrarium

  • The top is open, so air moves freely.
  • Humidity stays low.
  • For dry-loving plants like succulents, cacti and haworthia.
  • Watered sparingly, like a potted plant.
Closed terrarium: moss, driftwood and small plants in a sealed jar.
Closed terrarium: moss, driftwood and small plants in a sealed jar. Photo: Plantlover93, CC BY-SA 4.0 · Wikimedia Commons
Open terrarium: a wide glass bowl for cacti and succulents.
Open terrarium: a wide glass bowl for cacti and succulents. Photo: RJ Raawat, CC BY-SA 4.0 · Wikimedia Commons

Choosing a container

  • Use clear glass; tinted glass cuts the light.
  • Opening size: if your hand fits inside, everything is easier. Narrow bottles need long tongs and spoons.
  • Size: a ½–1 gallon jar or cloche is a good start for beginners (estimated). Very small containers are quickly outgrown.
  • Wash the container in hot soapy water and rinse well first; leftover dirt can encourage mould.

What you need

  • A glass container (lidded or open)
  • Drainage layer: gravel, pumice or expanded clay balls
  • Barrier: fine mesh or dry moss
  • Activated charcoal (aquarium charcoal; optional but recommended)
  • Soil: a light, organic mix for closed; cactus mix with sand and pumice for open
  • Plants, plus optional moss, stones and driftwood
  • Long tongs, a spoon, a small brush and a spray bottle

The layers, bottom to top

A terrarium has no drainage hole, so extra water collects at the bottom. The layers let that water sit away from the roots.

Step-by-step setup

  1. Spread 1–1½ in of gravel or pumice over the bottom. This is where excess water will collect.
  2. Sprinkle a thin layer of activated charcoal on top. It helps reduce odours and mould.
  3. Add the barrier: mesh or dry moss keeps soil from washing into the drainage.
  4. Add 2–3 in of soil. Building it slightly higher at the back gives a sense of depth.
  5. Take the plants out of their pots and gently shake off excess soil. Place the largest plant first, then arrange the smaller ones around it.
  6. Leave space between plants; they will grow. Keep leaves from pressing against the glass.
  7. Fill gaps with moss, stones or wood.
  8. Brush soil off the glass and leaves.
  9. Mist lightly with the spray bottle. Go easy on the first watering — too much water is harder to fix than too little.

Which plants work?

Choose slow-growing plants that stay small. Fast growers fill the container within a few months.

For closed terrariums

  • Fittonia (nerve plant)
  • Small ferns
  • Peperomia
  • Mosses
  • Small begonias
  • African violet (mini varieties)

For open terrariums

  • Haworthia
  • Echeveria
  • Small cacti
  • String of pearls (for a while)
  • Lithops (living stones)
Fittonia: one of the favourite closed-terrarium plants; it loves humidity.
Fittonia: one of the favourite closed-terrarium plants; it loves humidity. Photo: Why can't i get a cow, CC BY-SA 4.0 · Wikimedia Commons

⚠️ Don't put succulents in a closed terrarium. The high humidity soon makes them rot.

Light and placement

Place the terrarium in bright but indirect light. Direct sun heats the glass; inside a closed container it can get hot enough to cook the plants within hours. A north- or east-facing window works in most homes. If light is low, a small LED grow light is enough.

In low light, a small LED lamp is enough for a fern in a closed terrarium.
In low light, a small LED lamp is enough for a fern in a closed terrarium. Photo: Netha Hussain, CC BY 4.0 · Wikimedia Commons

Watering and care

Closed terrarium: light fog on the glass in the morning is normal and a good sign. If the glass stays completely fogged all day, there's too much moisture; leave the lid off for a few hours. If there's never any fog and the soil looks pale, give it a few sprays. Most closed terrariums go months without watering (estimated).

Open terrarium: water when the soil is completely dry, with just enough that nothing pools at the bottom. Every 1–3 weeks is enough in most homes (estimated).

In general: remove dead leaves straight away. Trim plants that grow too large. Fertiliser is hardly ever needed; slow growth is exactly what you want.

Common problems and fixes

White, cottony mould on soil or woodCommon in the first weeks. Remove it and leave the lid off for a few days. If it keeps coming back, water less.
Glass constantly fogged, drops running downHumidity is too high. Open the lid for a day, then close it again.
Leaves turning black, stems going softRot. Lift the plant out, soak up extra water with a paper towel, and hold off watering.
Plants stretching and turning paleNot enough light. Move it somewhere brighter or add a lamp.
Leaf tips drying outIn a closed terrarium, humidity has dropped; in an open one, it may be direct sun. Check placement and watering.

A short history

Growing plants in a sealed glass case began in London in the late 1820s. These containers became known as Wardian cases, and they made it possible to ship living plants on long sea voyages. Modern terrariums work on the same principle: a closed container keeps the moisture in.

A 19th-century Wardian case (Chelsea Physic Garden, London).
A 19th-century Wardian case (Chelsea Physic Garden, London). Photo: Daderot, CC0 · Wikimedia Commons

Frequently asked questions

Does a closed terrarium really never need water?

Not never, but very rarely. Once the moisture balance is right, water cycles inside the container. Still, check the fog on the glass and the colour of the soil about once a month.

Can I use only sand instead of soil?

A sand-heavy mix is fine for an open succulent terrarium. In a closed one, plants need organic soil that holds nutrients and moisture.

Is activated charcoal essential?

No, but in a closed terrarium it lowers the risk of odours and mould. Aquarium charcoal works.

How long does a terrarium last?

A well-built closed terrarium can last for years. As plants grow you'll need to trim them or swap some out.

Plants you can use in a terrarium

PeperomiaBoston fernHaworthiaEcheveriaString of pearlsAfrican Violet

Sources

Last updated: 2 November 2026