How to Make a Terrarium for Beginners | Simple Steps That Work

A beginner terrarium is a glass container garden built with drainage gravel, activated charcoal, potting soil, and small plants — and the whole thing takes about 20 minutes to assemble.

A terrarium turns a jar or fish bowl into a miniature indoor garden that nearly waters itself. The method works the same whether you’re using a mason jar, a spice jar, or a small tank: you layer materials from bottom to top, plant small slow-growing species, and place the container in bright indirect light. Here’s the exact build order that beginners get right on the first try.

What You Need for a Beginner Terrarium

The material list is short and most items cost under five dollars. You’ll need a clear glass container with no drainage holes, small gravel or pebbles for the bottom layer, activated charcoal to keep the water fresh, and a sterile potting mix — not garden soil, not fertilizer-heavy mix. For plants, choose small slow-growing types like pothos, ferns, or peperomia. A chopstick, pencil, or long spoon helps position the plants inside narrow containers, and a spray bottle handles the light watering that terrariums need.

The Six-Step Build Process

The layer order is the same across every reliable source, and it never changes because each layer serves a specific job. Follow this sequence and your terrarium will stay healthy for months.

1. Add the drainage layer. Spread a 1- to 2-inch layer of gravel or pebbles across the bottom of the container. The Pennsylvania Horticultural Society recommends a 2-inch base for most containers; the layer should take up one-quarter to one-third of the total container height. This keeps plant roots from sitting in water.

2. Add activated charcoal. Sprinkle a 1/4- to 1/2-inch layer of activated charcoal over the gravel. The charcoal absorbs odors, keeps the water fresh, and limits bacterial growth — Kew Gardens considers it a helpful addition, though it’s not strictly required if you’re patient with watering.

3. Add the potting soil. Add about 1 inch of sterile, moist potting mix on top of the charcoal. For deeper containers you can use more soil, but leave enough headroom for the plants and for air circulation near the top. The Spruce recommends patting the soil down gently to eliminate air pockets.

4. Plant your plants. Remove each plant from its nursery pot and gently tease apart any roots that are circling the root ball. Trim any damaged or yellowing leaves. Use your chopstick or spoon to dig small holes in the soil, place the plants, and firm the soil around them. Start with the largest plant and work to the smallest; put taller plants toward the back if your container will be viewed from one side.

5. Add finishing touches. Cover the exposed soil with a thin layer of moss, small stones, or pebbles. This keeps the soil from shifting during watering and gives the terrarium a finished look. A layer of sheet moss or sphagnum moss right above the charcoal can also help separate the soil from the drainage layer, but this is optional.

6. Water and position the terrarium. Mist the soil lightly with a spray bottle — the soil should feel moist, not soggy. Place the terrarium in a spot that gets plenty of bright, indirect light. Direct sunlight will overheat the glass and scorch the plants; a north- or east-facing windowsill works well. If you are making a closed terrarium, put the lid on and watch for condensation over the next few days.

Open vs. Closed Terrariums: Which to Choose

The container type determines how often you water and which plants thrive. A closed terrarium traps humidity and needs watering only every couple of weeks, making it ideal for moisture-loving plants like ferns and moss. Some condensation on the glass is normal, but heavy fogging means you have overwatered — lift the lid for a few hours to let it air out. An open terrarium dries out faster and needs watering about once a week, so it suits plants that prefer drier air, such as succulents and cacti (though succulents need more direct light than most terrarium placements provide).

If you are ready to choose a container and want to compare your options, our roundup of terrarium types and styles walks through the pros and cons of each shape.

Three Mistakes That Kill Most Beginner Terrariums

Overwatering. This is by far the most common failure. A closed terrarium’s water cycle recycles moisture, and adding more water than the initial light misting turns the soil into a soggy, rotting mess. If you see heavy condensation that doesn’t clear after a day, open the lid and let it dry out.

Direct sunlight. A glass container magnifies heat. Even an hour of direct afternoon sun can cook the plants and turn the inside into a miniature greenhouse at lethal temperatures. Always choose bright indirect light — near a window but not in the sun’s path.

Overcrowding. Plants need space for air circulation and for their own growth. Cramming too many plants into a small jar leads to rot within weeks. Leave several inches between plants and choose slow-growing species so you don’t have to repot every two months.

Care Routine for a Healthy Terrarium

Check the soil moisture every few days by touching the surface or looking for condensation on the glass. For a closed terrarium, you may not need to water for weeks — just mist the soil when it feels dry. For an open terrarium, water about once a week with a spray bottle or a small stream, using only enough to moisten the soil. Remove any yellow or dead leaves as they appear, and if the plants outgrow the container, move them to a larger one. Terrariums do not need fertilizer; the soil already contains enough nutrients for slow-growing plants, and extra fertilizer can burn their roots.