Terrariums are an easy way to grow plants indoors. Start by choosing a clear glass container with a wide opening. Gently add fine gravel to your container. Top with a thin layer of aquarium charcoal. (Both of these items can be purchased at a pet store.) Then add moist potting soil. These miniature landscapes can hold a collection of colorful plants for display or just show off one plant. Good choices include ferns, peperomias, succulents, begonias, Irish moss, miniature orchids, kalanchoes, and African violets.