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A Step-by-Step Guide to Building Your First Terrarium (2025)

Updated: 2025

A Step-by-Step Guide to Building Your First Terrarium

Quick answer: To make a terrarium, choose open or closed style, add layers in this order—drainage (pebbles), charcoal, soil, then plants + decor—and place it in bright-indirect light. Open terrariums suit succulents/cacti; closed terrariums suit humidity lovers like mosses and mini ferns. For a custom plant list tailored to your room’s light and humidity, try the AI Plant Doctor Tool.

Open vs. Closed Terrariums

Open Terrarium

  • Best for: Succulents, cacti, peperomia varieties that prefer airflow.
  • Light: Very bright-indirect; a little morning sun is OK.
  • Watering: Infrequent; let soil dry between sips.

Closed Terrarium

  • Best for: Moss, mini ferns, fittonia, pilea—plants that love humidity.
  • Light: Bright-indirect (no direct sun—risk of “greenhouse” overheating).
  • Watering: Minimal—system recycles moisture; vent occasionally.

Takeaway: Choose the style that matches your plants—not the other way around.

Materials & Tools Checklist

  • Glass container (open bowl, jar, cloche, or lidded vessel)
  • Small drainage stones/pebbles or leca
  • Activated charcoal (odor and mold control)
  • Terrarium soil (succulent/cactus mix for open; moisture-retentive mix for closed)
  • Plants (see beginner lists below)
  • Long tweezers/chopsticks, spoon, small brush, spray bottle
  • Decor (sand, rocks, driftwood, miniature accents—optional)

Layering: The No-Fail Formula

  1. Drainage (1–2 in / 2–5 cm): Pebbles or leca to catch excess water.
  2. Charcoal (thin layer): Filters odors, discourages mold.
  3. Soil (enough for roots): Mound slightly to create landscape contours.
  4. Planting: Make holes, gently place plants with tweezers, firm soil around roots.
  5. Decor & Clean-up: Add stones, brush soil off leaves, wipe inside glass.
  6. Initial Water: Lightly mist/soak depending on style (see below).

Pro tip: Slope soil from back (higher) to front (lower) for depth and visibility.

Beginner-Friendly Plant Lists

For Open Terrariums (Airy & Drier)

  • Haworthia, Gasteria, small Echeveria
  • Peperomia (prostrata, hope, ruby cascade—avoid heavy overwatering)
  • Crassula, Sedum minis

Watering: Tiny amounts every 2–4 weeks; ensure airflow.

For Closed Terrariums (Humid & Lush)

  • Mosses (sheet/cushion), miniature ferns
  • Fittonia (nerve plant), Pilea depressa, Pilea glauca
  • Selaginella, small Calathea/Maranta cultivars

Watering: Light mist once at setup; then watch condensation and vent as needed.

CTA: Not sure which plants match your light and humidity? Get a personalized shortlist from the AI Plant Doctor Tool.

Where to Place Your Terrarium

  • Bright-indirect light is the sweet spot.
  • Avoid hot direct sun—it can cook plants inside glass.
  • Consider a small LED grow light if your room is dim.

Watering & Maintenance

Open Terrariums

  • Water sparingly; allow soil to dry between waterings.
  • Brush off dust; rotate monthly for even light.

Closed Terrariums

  • Watch the glass: Heavy condensation = too wet (vent lid). No condensation = likely too dry (mist lightly).
  • Trim growth to prevent touching glass (reduces rot).

Troubleshooting

  • Mold or algae on glass: Vent more often, reduce watering, add fresh charcoal.
  • Plants rotting at base: Too much moisture; increase airflow, remove affected pieces, replace wet soil if needed.
  • Leggy, pale growth: Insufficient light—move closer to a bright window or add a grow light.
  • Gnats: Allow soil to dry more; cover soil temporarily with sand; use sticky traps outside the glass.

Takeaway: Most issues come from too much water or too little light.

Design Tips (Small Apartments & Statement Pieces)

  • Go vertical: Tiered shelves or wall-mounted ledges for multiple small terrariums.
  • Odd numbers: Style in clusters of 3 or 5 for balanced compositions.
  • Mix heights: Combine a tall cloche with low bowls for depth.
  • Consistent palette: Repeat stones/sand colors to tie displays together.

Real-World Example

Case study (2025): A VerdeBotany user built a closed terrarium with moss, fittonia, and selaginella but struggled with fogged glass and yellowing leaves. The AI tool flagged excess moisture and low light. After venting daily for a week and moving to brighter-indirect light, growth stabilized and the glass stayed clear.

Personalize Your Terrarium with Our AI Tool

Upload a photo of your spot, tell us your window direction, distance, and whether it’s open or closed, and get a custom plant list + care plan (watering, venting schedule, and light placement).

Try the AI Plant Doctor Tool →

Helpful Internal Links

Terrarium FAQ (2025)

Do I need activated charcoal?

It’s highly recommended—charcoal helps control odor and microbial growth, especially in closed terrariums.

How often do I water a closed terrarium?

Rarely. Start with a light mist at setup, then watch condensation. Vent if too wet; add a few mists if it looks dry for days.

Can I put succulents in a closed terrarium?

No—succulents prefer dry air. Use an open container with fast-draining soil and infrequent water.

What size container is best for beginners?

Medium bowls or jars (6–10 in / 15–25 cm) are easiest to plant and maintain.

Where should I keep my terrarium?

Bright-indirect light, away from hot direct sun or vents. A small grow light can keep things happy year-round.