The Indoor Garden You Don't Have to Water

Before You Begin
Choose a vessel, clean it, then decide where it's going to live. Avoid rooms with extreme temperatures (like an unheated porch). Then choose the plants. "Plants that work best are small, slow-growing, shade-loving, and tolerant of humidity — like ferns, mosses, or violets," says Tovah Martin, coauthor of The New Terrarium.

Spread a one-inch layer of pebbles or gravel in the base of the terrarium. Top that with a layer of charcoal to help filter water and prevent fungi and mold from forming once the terrarium is closed.

Spread two inches of potting soil on top of the charcoal, creating a small mound at the center, where you'll place the plant.

Dig a hole in the mound of soil and place the largest plant inside, making sure that all the roots are buried so they won't dry out. If you're using multiple plants, repeat this step, leaving space between plants so they won't crowd one another.

Add a decorative layer of stone or moss around the plants, suggests Tassy Zimmerman, co-owner of Sprout Home, a home and garden shop in Brooklyn, NY. Trim leaves that extend beyond the edge of the terrarium base. Then use a spray bottle to lightly mist the soil.

Let the terrarium air out for a few days before closing it. (Trapping excess moisture can cause mold to grow.) Once the lid is on, the elements inside will create an ecosystem to help the plant thrive, so there's no need to really water. Every few weeks, open it, feel the soil, and if it's dry, lightly mist, then repeat these steps.

A curved vase, empty jar, or domed cake platter all make for a beautiful terrarium. (To left, glass covered cake stand, $25; surlatable.com).