If you're looking for an indoor gardening project or would simply like to expand your plant-growing horizons, consider building a terrarium. A terrarium is a miniature ecosystem built inside of a glass container. Choosing the right plants and mixing the ideal blend of foundation materials will allow your terrarium to be self-sustaining. A properly set up terrarium will need little input from you other than occasional watering, and it will provide you with a unique piece of living art for your home.
Choose a clear glass container. Terrariums can be grown in completely enclosed containers, such as a jar with a lid, or in open containers, like an old aquarium. Beginners will have the best luck with an open terrarium. Open terrariums will require more frequent watering, but closed terrariums are more prone to disease.
Wash your container with dish soap. You can also wipe down your container with a solution of 10 parts water to one part bleach. Rinse it very well with hot water to remove any bleach or soap residue.
Place a layer of pebbles about two inches thick on the bottom of your terrarium for drainage.
Cover the pebbles with about half an inch of activated charcoal. The charcoal purifies the air and soil and works to prevent mold or disease.
Spread an inch or two of moist sphagnum moss over the charcoal. The sphagnum moss acts as a filter and prevents the soil from trickling down into the drainage layers below.
Cover the sphagnum moss with two inches of potting mix. Regular potting mix will work fine, or you can use a specially blended terrarium potting mix.
Install your plants. Many houseplants can adapt to a life in a terrarium, although in a closed terrarium you may want to use only plants that thrive in a high humidity environment. Choose plants that are slow growing and that stay small, so that they won't outgrow the terrarium too quickly. You will also want to consider the light levels in your terrarium. Swedish ivy (Plectranthes australis) does well in low light areas, while African violets (Saintpaullia spp.) and pitcher plants (Sarracenia spp.) are well suited for moderate light conditions. For bright light, consider sundew (Drosera spp.) or asparagus fern (Asparagus plumosus). Make sure all your plants have similar moisture requirements.