How to Make a Terrarium, a Self-Sustaining Ecosystem That Thrives for Years

Terrariums are self-sustaining ecosystems perfect for growing plants that thrive in high humidity, like tropical ferns, mosses, and air plants. These miniature greenhouses are usually made in small glass containers filled with pebbles, charcoal, potting medium, and plants. They thrive with minimal care, making them popular amongst gardeners of all skill levels.

You can make a terrarium at home using a few basic supplies and low-maintenance plants. In this step-by-step guide, we'll show you how to create a terrarium and give you tips for caring for and cleaning it so it thrives for years.

How to Make a Terrarium

Choose a Container

Terrariums should be built in clear containers with a large enough opening to arrange your plants to your liking. We used kitchen canisters, which are readily available and inexpensive. Ideally, a closed container with a lid will encourage humidity and help plants thrive. However, you can also build a terrarium in a container with an opening.

Search your attic, basement, and cupboards for unique vessels, like clear soup tureens, kitchen jars, and empty bottles. Whatever you choose, be sure that it is smooth, clear glass. "Colored glass will block the sunlight your plants need to thrive," says Todd Carr, gardener and founder of Hort and Pott.

Choose Your Plants

The terrarium plants you choose depends on the type of container you're using. Closed containers are ideal for plants that need a lot of humidity to thrive, like moss and ferns. Succulents and cacti won't survive in a closed terrarium, but can be planted in a terrarium with an opening. Here's a list of some options to consider:

• Air plants
• Small ferns
• Pincushion moss
• Nerve plant
• Peperomia
• Spiderwort

Add Drainage Layers

Deposit a base layer of small pebbles or gravel about 1-inch thick to the bottom of your container. This layer helps with drainage, as terrariums don't typically have drainage holes for water to escape out of. Next, add a thin layer of horticultural charcoal over the gravel or pebbles. Charcoal adds organic matter to your terrarium and helps absorb any chemicals or odors.

Add Potting Soil

Top the gravel and charcoal with a layer of damp potting soil. A soilless potting mix without fertilizer is ideal. Do not use garden soil, as it is too heavy and will compact in your terrarium.

Add Plants

Nestle your selection of plants neatly into the soil so the roots are covered and any leaves, petals, and stems do not touch the glass. Add other touches if you'd like, like figurines and uniquely shaped rocks, to personalize your terrarium.

How to Care for Your Terrarium

While they're relatively easy to make, terrariums require some basic care to ensure the plants inside them thrive.

Water

The worst thing you can do is overwater your terrarium plants. Occasionally misting the plants with water is typically enough. If there is water on the foliage after misting, let it dry before placing the lid on the terrarium.

Terrariums act like tiny greenhouses, resulting in condensation on the inner walls. The condensation then drips down and waters the plants. If you find that too much condensation forms, give the terrarium a little less light or remove the top for two hours.

Light

Most terrariums prefer being kept in a spot with diffused light, such as by a south-facing window. Never place your terrarium in direct, bright sunlight; the afternoon heat can damage the foliage.

Humidity

Terrariums like humidity. Keeping the terrarium closed is what traps the humidity and keeps your plants happy. Therefore, a little ingenuity is called for if you're using a container without a lid. "If there is no lid on your terrarium, you can use a glass plate on the top," Carr says. "Or if it's a narrow-necked bottle, use a lightbulb to block the opening and create extra humidity."

How to Clean Your Terrarium Container

Clean the inside once you begin to see water spots or algae buildup—this typically occurs once a week. Reaching the corners of a container isn't always easy, which is why you should keep tools on hand, like long-handled tweezers and scissors.

Remove Dead Debris

Use long-handled tweezers and scissors to either pick up dead leaves or prune leaves off the plant or edge of the glass, Carr says, adding that chopsticks can work as well.

When even tweezers won't help you hit those out-of-reach corners, a wire hanger will work. "Use a wire hanger to create a little hook or loop to move leaves and plants out of the way to gain access and see what you're maintaining beneath," says Carr.

Scrub the Container

Attach a small piece of sponge to a sturdy structure (a chopstick, a wooden spoon, or thin bamboo will work) with floral wire. Use the sponge to wipe the inside of your glass terrarium clean.