Terrariums are clear glass or plastic containers that are filled with small plants. They are a good way to keep indoor plants with a minimum of care and mess. Terrariums come in either open or closed varieties. Open terrariums are good for building high humidity, although they lose some of this through the opening. Closed terrariums retain more humidity and need less watering. Good flowers for closed terrariums are those that will stay small and thrive in warmth.
Ardisia are actually shrubs, but they have lovely, long, dark green leaves and produce pinkish-white flowers in the springtime. Ardisia are good for closed terrariums because they need only a minimum winter temperature of 50 degrees Fahrenheit in order to live. Ardisia are also good for closed terrariums because they grow quite slowly, so it will be obvious long before the fact that you may need to replant your ardisia in a larger container. According to the website botany.com, if you do need to replant ardisia, you should do it during either February or March.
African violets make excellent flowers for closed terrariums. They grow to a fairly small height and width, need little water and thrive in the same indoor temperatures as humans do. They grow best in temperatures of 65 to 70 degrees Fahrenheit. They will survive at slightly higher or lower temperatures, but flowering will be reduced. African violets produce beautiful purple flowers that make them an especially attractive indoor plant.
Calendulas bloom in happy-looking round yellow, orange or reddish flowers. They tend to bloom in the warm summer months but can still continue all the way into fall. They do not need much water and are tolerant of less-than-ideal soil, but they can be prone to plant disease and mildew. Calendula flowers are also edible; not only are they non-toxic, but they are also sometimes used as a more affordable alternative to saffron.
There are several types of begonias. Depending on which variety you have, their flowers can be red, pink, yellow or white, but all begonia flowers have a bright yellow center. Begonias are notoriously easy plants to grow indoors. They like warm climates but grown well in a wide range of light, and even continue to grow in the shade. They are at little risk for diseases and thrive in loose soil. Begonias do grow better if their dead leaves, stems and flowers are trimmed or removed regularly.