There is something magical about a terrarium. It’s a miniature, living world—a tiny, self-contained garden thriving inside a glass vessel. They are a beautiful way to bring a touch of nature indoors, and the best part is that they are surprisingly easy to create and care for.

If you’ve always wanted to build your own little green world but weren’t sure where to start, you’re in the right place. This simple, step-by-step guide will walk you through everything you need to know to build your first successful terrarium.

Step 1: Open vs. Closed — Choose Your World

Before you buy a single plant, you need to make one crucial decision: will your terrarium be open or closed? The answer will determine everything else.

• Closed Terrariums: These are containers with a lid or a seal. They create a high-humidity, self-sustaining environment that essentially waters itself through condensation and evaporation. Think of it as a miniature rainforest.
• Best Plants: Moisture-loving tropicals like ferns, moss, nerve plants (fittonia), peperomia, and polka dot plants.
• Open Terrariums: These are unlidded containers like bowls or vases that allow for plenty of airflow and low humidity. Think of it as a miniature desert.
• Best Plants: Arid, drought-tolerant plants like succulents, cacti, and air plants.

The Golden Rule: You cannot mix these two types of plants. Succulents will rot in the humid environment of a closed terrarium, and tropical ferns will dry out and wither in an open one.

Step 2: Gather Your Supplies

Once you’ve chosen your path, it’s time to gather your materials.

• The Vessel: Any clear glass container will work. Get creative with mason jars, cookie jars, fishbowls, or classic terrarium cases.
• The Drainage Layer: Small pebbles, gravel, or LECA (lightweight expanded clay aggregate). This creates a reservoir for excess water to prevent the plant roots from rotting.
• The Divider: A small piece of window screen, landscape fabric, or a layer of sphagnum moss. This stops the soil from mixing with your drainage layer.
• Activated Charcoal: You can find this at any pet store or garden center. A thin layer acts as a natural filter, keeping the terrarium fresh and preventing mold, which is especially important for closed systems.
• The Right Soil (Substrate): For a closed/tropical terrarium, use a well-draining, standard potting mix. For an open/arid terrarium, use a gritty cactus and succulent mix.
• The Plants: Choose small, slow-growing plants that fit the theme of your terrarium.

Optional Tools: Long tweezers or chopsticks for placing plants, a small paintbrush for cleaning dirt off the glass, and a spray bottle.

Step 3: The Step-by-Step Assembly

Here comes the fun part! Let’s build your terrarium layer by layer.

The First Watering: Water your new creation lightly. For a closed terrarium, a few spritzes from a spray bottle is all you need to get the cycle started. For an open terrarium, water the base of each plant until the soil is moist.

Start Clean: Wash and thoroughly dry your glass container.

Drainage First: Add a 1- to 2-inch layer of your pebbles or gravel at the bottom.

Divide and Conquer: Place your mesh divider or sphagnum moss on top of the drainage layer.

Filter It: Sprinkle a thin, even layer of activated charcoal over the mesh.

Add the Soil: Add a layer of the appropriate soil, making it deep enough to comfortably house your plants’ roots (usually 2-3 inches).

Time to Plant: Carefully remove your plants from their pots and gently loosen their root balls. Use your fingers or tweezers to dig small holes, place your plants inside, and gently pat the soil around them. A good design tip is to place taller plants in the back.

Decorate: This is where your creativity shines! Add a layer of moss, a few interesting rocks, or a piece of driftwood to complete the look.

Step 4: Caring For Your Miniature World

• Light: Place your closed terrarium in a spot with bright, indirect sunlight. Direct sun will scorch the plants. Your open terrarium will want bright, direct sunlight for several hours a day.
• Water: This is where people go wrong. A closed terrarium may only need water once every few months, if ever! If you see no condensation on the glass for a few weeks, give it a tiny bit of water. A open terrarium should only be watered when the soil is completely dry to the touch (usually every 2-4 weeks).
• Maintenance: Prune any dead or yellowing leaves to keep things tidy, and occasionally wipe down the inside of the glass with a paper towel.

Congratulations! You’ve just created your own beautiful, thriving mini-ecosystem. Now sit back and enjoy the pleasure of watching your little world grow.