Selecting the appropriate plants for your terrarium is very important. All of the plants must be compact, slow-growing, and require the same growing conditions in order to survive. Use plants that need the same amount of water and sunlight. Small shade and water loving plants such as miniature orchids, begonias, ivy and fern are good choices for a terrarium.
Miniature orchids do very well in the warm, moist conditions that terrariums provide. Pleurothallis is a genus of miniature orchid with 1,200 species. The pleurothallis barbulata is a tiny orchid that grows no more than 1 inch. It has bright orange flowers with a dark red or purple overlay. Pleurothallis grobyi has purplish leaves about 3 inches long with bright yellow flowers. Pleurothallis flexuosa grows to about 4 inches tall. The yellow and purple spotted flowers bloom all year long and are covered with white wool-like hairs. These miniature orchids love the high humidity that terrariums provide and many plants can be accommodated in a small space.
Many begonia species are well suited to the terrarium where they will add a splash of color not only from their flowers, but also from their leaves. Begonia "Little Darling" is a neat, miniature begonia with 1-inch leaves marked with brown and chartreuse green. It has a mounding habit and matures to 6 to 8 inches tall. Begonia thelmae var. Major is an easy-to-grow variety with 2 inch cupped leaves that are dark green above and deep burgundy below. It has a creeping habit and produces a few pinkish-white flowers throughout the year. Begonia bipinnatifida is a rare species with fine, needle-like leaves that are dark green with a deep burgundy underside. These plants occasionally produce small, pinkish flowers.
Hedera helix is a miniature ivy with tiny, pointed, dark green leaves. Also called "Itsy Bitsy," this ivy grows in small, bushy mounds. Hedera helix "Oak Leaf" is the easiest to grow of all the miniature ivies. It has dark green, oak-leaf foliage. Hedera helix "Spetchley" is a small ivy with thick, woody, dark stems and tiny, deep green, bird's foot-shaped leaves. All of these ivy plants are ideal for terrariums as they are small-leaved and have a small growth habit.
Lemon button fern (nephrolepsis cordifolia) stays less than 12 inches tall and sends creeping runners that sprout new plantlets. It has long strands of nearly round chartreuse frondlets. When actively growing, it has a subtle lemon scent. Adiantum raddianum fragrantissimum has elegant, arching, blackish stems that accent the dark, narrow fans of this heirloom "Maidenhair fern." Adiantum raddianum pacotti has erect, compact fronds covered with deeply lobed segments shaped like teardrops.