Terrariums are tabletop ecosystems that are fun to make and easy to tend. “Terrariums allow you to enjoy plants up-close and to add greenery to your home, even in a very small space,” says designer Maria Colletti, terrarium workshop leader and author of Terrariums: Gardens Under Glass. “Because you design them yourself, every creation is unique and personal.”
Terrariums can be lidded, which allows heat and moisture to be contained, or open on the side or top. “You can use many different kinds of plants, but tropical plants like the humid environment inside a closed terrarium,” says Colletti. “Succulents or cacti need the drier environment of an open container.” You also can add decorative touches such as driftwood, shells or other objects to mimic a tiny seashore, jungle, or desert scene. There’s no limit but your own imagination!
Here’s how to build your own little world under glass:
How To Make A Terrarium
Step 1: Choose a Container
Use either closed containers, such as miniature greenhouses or lidded jars, or open containers, such as globes, fish bowls, or lanterns. Or repurpose items such as Mason jars or recycled jam jars. Just make sure the container is large enough for you to fit a few plants inside without the greenery touching the sides of the container, says Colletti. Of course, the wider the opening, the easier it is to work.
Step 2: Select Your Plants
There are tons of choices for terrarium plants, but stick with some tried-and-true options for your first time. Plants such as fittonia, peperomia, button fern, creeping fig, and selaginella like the humid conditions of a closed terrarium. For open containers, opt for plants that require more air circulation or drier conditions such as tillandsia, echeveria, burro’s tail, jade plant, and haworthia.
Avoid plants that are notoriously fussy, such as a maidenhair fern, or fast growers, such as pothos (or you’ll need to prune frequently—which is fine, if you don’t mind!). Two-inch pots are a good size as starter plants, says Colletti. Dried preserved moss is also useful for covering any bare soil and giving a more finished look to your design.
Step 3: Layer Your Terrarium
Follow the same basic steps whether your terrarium is closed or open. Start with a drainage layer so roots don’t rot. Gravel, sand, or lava rock works well, and you’ll put down a thin layer on the bottom (about ¼ to one inch deep, depending on your design and container size). In closed terrariums, add some activated charcoal, which helps absorb excess moisture, around the perimeter of the container or around each plant, says Colletti.
Next, layer on your soil or add soil only in the center of the container where you’ll place plants. The planting medium should be deep enough to accommodate your plants’ roots. Start with your tallest plant first, removing it from its pot, and nestling it into the soil in its new home. Add the remaining plants. A chopstick or paintbrush can help you smooth soil into place.
For closed containers, finish by covering the bare soil with moss. Use a spray bottle and lightly mist the soil at the base of each plant. If it’s a lidded container, close the top. Put your terrarium in bright indirect light—but not direct sunlight, which will scorch the plants. If you don’t have sufficient natural light, a grow light also works.
How To Water Your Terrarium
Typically, you’ll need to spritz plants about once a week, says Colletti. A little condensation is normal (and desirable) in a closed container. But if it seems like it’s too wet, cut back on watering and keep the lid off for a few days.
For open containers, you’ll probably only need to water every week to ten days. Use your finger to check the soil; if it still feels damp, wait and recheck again in a few days, says Colletti. Most open containers only need a tablespoon or two of water every couple of weeks.
How To Care for Your Terrarium
A healthy terrarium mostly takes care of itself with occasional maintenance from you. Remove dying plant matter immediately. Trim back plants that are getting too big, shading out others, or touching the sides of the container. It’s not necessary to fertilize because you want the plants to grow slowly, says Colletti. In general, your terrarium will last a few months to a year before you’ll need to redesign and replant it.
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